Cichlid Room Companion

Internet lectures

Environmental Balance in the Freshwater Aquarium

By , 1996. printer

Classification: Captive maintenance.

" Fishroom talk taking place on 1996-Jul-31 "

Pete says: 10:00pm fishroom time

JuanMi says: Well ladies and gentleman, tonight, in our cichlid meeting, we have a special guest. Roger Miller, who is going to tell us about the environmental balance in the freshwater aquariums, I hope you all enjoy, thanks Roger

BobJones applauds!

Rgrmill says: This talk might run a little long, so I'm planning a couple short breaks for questions before the end of the talk. That way you can ask questions before the topics get stale.

Rgrmill says: The topic contains no reference to cichlids, so you might wonder what I could say that would interest a keeper of cichlids.

Rgrmill says: My talk will be fairly general - mostly about aquarium keeping rather than cichlid keeping - but I'll mention cichlids here and there as I go.

Rgrmill says: Before I go any farther I'd like to describe very briefly why "environmental balance" is important.

Rgrmill says: An aquarium provides an environment for its inhabitants and even a simple aquarium environment has many interrelated components that are under the influence or control of the aquarium keeper.

Rgrmill says: If the components are far out of balance, then the conditions in the aquarium will change continuously, sometimes rapidly and usually for the worse.

Rgrmill says: A lot of money, time and labor goes into keeping fish alive in unbalanced aquaria.

Rgrmill says: If the components are close to a balance, then the conditions in the aquarium will change only gradually and a much better environment can be maintained with a relatively small investment of time, money and labor.

Rgrmill says: A perfect balance - one where there is no change at all - probably doesn't exist. However, some systems may change so gradually that they appear to be stationary.

Rgrmill says: The basics of maintaining a balanced environment in a freshwater tank are fairly well established in the hobby and most of this talk will cover one point of view about some of those basics.

Rgrmill says: The topic of "environmental balance" extends far beyond the basics. It provides some of the most advanced discussion available in the hobby.

Rgrmill says: I don't intend to go very far into anything controversial or technically advanced.

Rgrmill says: Just the same, I will be covering a few ideas that I regard as "advanced" aquarium keeping - things that I would never advise a beginner to try.

Rgrmill says: Most people want two things from an aquarium. They want it to maintain selected organisms (cichlids, for instance) in vigor and good health and they want it to maintain them that way without a lot of work.

Rgrmill says: Its my experience that when an aquarium fails to meet one of these conditions the problem can often be traced to high nutrient concentrations.

Rgrmill says: Nutrients tend to build up in aquariums as time passes until problems begin to appear. The problems are made worse by high biological loads which normally implies higher feeding rates and so more nutrients.

Rgrmill says: Normally in order to improve health and vigor, we prescribe larger and/or more frequent water changes (more work) to fix the problems.

Rgrmill says: Natural systems - my model for environmentally balanced systems - behave very differently.

Rgrmill says: For one thing, dissolved nutrients don't tend to accumulate. The smallest accumulations of dissolved nutrients are found where water residence time is greatest. The longer water stays in a lake of pond, the lower the nutrient levels tend to be.

Rgrmill says: Also, the problems aren't aggravated by high biological loads. The most effective reductions in dissolved nutrients occur in wetlands, where the bioloads are the highest.

Rgrmill asks: Wouldn't it be nice if we could get at least some of this natural behavior in our aquariums?

Rgrmill says: The actual mechanisms that regulate nutrient levels in natural waters are highly variable and complex, but the principle involved is relatively simple.

Rgrmill says: For a body of fresh water, organic terrestrial detritus and dissolved minerals in influent water are the main sources of nutrients.

Rgrmill says: Dissolved nutrients are taken up by plants - mostly algae - that use light and the nutrients to build biomass. Some of the algae is eaten and some of it settles out in sediments.

Rgrmill says: Terrestrial detritus is either eaten or settles out in sediments.

Rgrmill says: Nutrients from both sources are passed on through the food chain or more appropriately, through the trophic web. Each organism in the web can store the nutrients in their own biomass or return nutrients to the water.

Rgrmill says: Stored nutrients can be passed through the web by predation, incorporated in sediments when the organism dies, or exported from the system when the organism leaves the system.

Rgrmill says: Nutrients returned in an organism's wastes may remain in solution or escape from the system as a gas.

Rgrmill says: The net effect is; natural systems use light to pump nutrients into the trophic web, and the web stores them in biomass, loses them to the air or sediments, or exports them to other systems.

Rgrmill says: We don't see this sort of behavior in most aquaria.

Rgrmill says: Often, we don't provide enough light to run the system.

Rgrmill says: Also, it's difficult - maybe impossible - to set up an aquarium with the variety of physical environments found in natural systems.

Rgrmill says: And certainly we don't build an effective trophic web.

Rgrmill says: I'll break for a few minutes now for questions.

Rgrmill says: Afterwards I'll try to give a general description of a few different kinds of environmental systems and how they work in aquaria.

Juanmi raises his hand.

Rgrmill asks: So, are there questions or comments that I can handle at this point? Juan?

JuanMi asks: Roger it is at all possible to use light in an aquarium as a source of nutrient absorption, with the high biomass that we aquarists use to keep?

Rgrmill says: I think its not only possible, Juan, but critical for aquariums where we try to balance different biological influences.

JuanMi says: thanks

Pete raises his hand

Rgrmill asks: Pete?

Pete asks: Roger, are you saying that we can use light and more light to stabilize the aquarium?

Rgrmill says: I'll go into it in a little more detail later, but yes. I'm saying that light, lots of light is very important.

Pete nods his head in understanding.

Brianl raises his hand.

Rgrmill asks: Yes Brianl?

Brianl asks: When you say nutrients what exactly do you mean...I'm assuming nitrates, phosphates, silicates.. stuff like that... things I generally associate with algae growth, but what else?

Rgrmill says: What I have in mind as nutrients is primarily any biologically available form of the 6 or 7 most important elements (C, O, N, P, S, and so on). But also essential organic compounds, like thiamin.

Brianl says: okay.. thanks.

BobJones raises his hand

Rgrmill asks: BobJones?

BobJones asks: How much light exposure do you suggest? For example I leave my light on for at least 16 hours. Would this be sufficient?

BobJones asks: Will it harm the fish?

Rgrmill says: Bob, once the light duration exceeds 10 hours, or so, its the intensity of the light, rather than the duration that matters. Since the light we can provide a tank is generally going to be less than direct sunlight (much) and in most cases low in UV, I doubt there would ever be a risk to the fish.

BobJones says: Thanks

Rgrmill says: I'll return to the talk now.

Rgrmill says: The word 'balance' appears here in two different contexts.

Rgrmill says: The first (and simplest) usage expresses the physical laws of conservation of mass and energy; it is just a budget for a chemical component or for energy.

Rgrmill says: The amount of any component in a system changes over a period of time by the difference between the amount of the component added and the amount removed in the same period.

Rgrmill says: Stability in an aquarium means that all components must be physically balanced. Otherwise some component will build up over time until problems appear. For everything that you add to an aquarium, there must also be an acceptable means of removing it.

Rgrmill says: The second usage is similar but more complicated. An environment contains numerous organisms. Each organism utilizes some components of its environment and creates other components.

Rgrmill says: Daphnia , for instance, consume algae and produce more daphnia, plus wastes.

Rgrmill says: Algae consume the daphnia's waste and produce more algae.

Rgrmill says: An environment is balanced when the organisms exist in proportions so that the amount of different components in the system remains stable.

Rgrmill says: With our algae-daphnia system, the environment is balanced when the population of daphnia and the algae mass are about constant.

Rgrmill says: Aquaria contain a large number of chemical and biological systems. 'Open systems', 'closed systems' and 'cycles' are types of systems that we deal with in aquaria.

Rgrmill says: Open systems interact with their surroundings. Some chemical component or organism moves between the system and its surrounds, so the concentration or population is influenced by conditions outside the aquarium outside the aquarium.

Rgrmill says: We don't usually seal our aquaria, so there is a constant exchange of atmospheric gases. Aquaria are open systems with respect to water, nitrogen, oxygen and carbon dioxide, as well as anything else that happens to be in the air.

Rgrmill says: Feeding causes another kind of open-system behavior. Food is added to the aquarium on a regular basis, but there is no usual means of removing food wastes on an equally frequent basis. Many components of food build up over time.

Rgrmill says: Water changes provide a way to remove accumulated food products and wastes. With a water change, the aquarist manually opens the system.

Rgrmill says: Water movement is a critical characteristic in open systems. Diffusion governs the movement of carbon dioxide and oxygen between air and water, but diffusion is slow.

Rgrmill says: Without water movement a thin layer at the top of the water is aerated, and the rest of the tank is essentially isolated from the air.

Rgrmill says: To correct that it is important for the water to be in continuous movement; turbulent motion in fact is important for good mixing.

Rgrmill says: Open systems can be very stable because they depend on external conditions that can be constant or slowly changing. Stabilizing a system often means opening the system; increasing circulation and doing large and more frequent water changes.

Rgrmill says: In closed systems there is no interaction with the surroundings and the concentration of all components is determined entirely by internal conditions.

Rgrmill says: Systems can be closed for some components and open for others. Realistically, system are generally neither perfectly closed or perfectly open.

Rgrmill says: In one 'ideal' aquarium, the system is closed with respect to all chemical and biological components, but not to light. All the nutritional needs of every tank inhabitant are provided from a pool of nutrients of nutrients added before the system was sealed.

Rgrmill says: Oxygen use and carbon dioxide production by respiratory animals and microbes just balances the carbon dioxide use and oxygen production by plants.

Rgrmill says: Dietary calories are provided by light. Evaporation is prevented and water use during photosynthesis and water production during metabolism just balance.

Rgrmill says: This is a zero-maintenance aquarium. I understand that you can actually buy simple closed-system aquaria consisting of water, shrimp and algae sealed in a glass sphere. With light, the systems can work for years.

Rgrmill says: Simplicity and low maintenance are the up side of closed systems. The downside is that they usually aren't stable.

Rgrmill says: Successful closed systems require coordinated and complete cycling of every component; if the cycle fails for any component then the entire system stops working.

Rgrmill says: Cycles are complex, idealized systems that are closed in one component.

Rgrmill says: In a cycle a single chemical component is used and altered and reused and eventually returned to its original state by the actions of many different mechanisms and organisms.

Rgrmill says: Complete cycles normally require systems that include a lot of different physical and chemical environments, implying a large scale.

Rgrmill says: In small systems the cycles are usually broken because we promote open system behavior and because we don't provide the kind of physical and chemical variety necessary to complete a cycle.

Rgrmill says: But even with the small scale and homogeneous conditions of an aquarium, partial cycles and shortened cycles can be important to maintaining good conditions in an aquarium.

Rgrmill says: Ammonia wasted by fish provides the nitrogen needed for the growth of algae; the nitrogen in the algae is used by algae-eating fish. This is a simple and effective (although partial) cycle.

Rgrmill says: As a result, algae eating fish need only supplemental feeding and the aquarium is free of nuisance algae growth.

Rgrmill says: If for some reason the cycle doesn't work, then the aquarium is more difficult to care for.

Rgrmill says: If there are no algae eating fish, then the tank requires constant cleaning. Without algae, the fish require more food and nitrogen builds up in the tank.

Rgrmill says: I should point out here that 'The Cycle' referred to in the hobby isn't a cycle at all.

Rgrmill says: 'The Cycle' is just a one-way biological pipeline that routes nitrogen from its ammonia form (which is useful and important but potentially toxic) to its nitrate form (which is safer, but has much less biologic value).

Rgrmill says: Of course, there are a many different cycles, and most cycles involve more than two organisms. Moreover, each organism is involved in many different cycles.

Rgrmill says: Every organism and the concentration of each chemical component in a system is linked through a series of interrelated cycles; everything in the system is interdependent.

Rgrmill says: Nature provides a complex and redundant 'web' of interrelationships. On a very large scale (e.g. Earth) the web is stable and robust.

Rgrmill says: At the scale of an aquarium, it probably isn't possible to reproduce the robust behavior, but it may be possible to use similar but simpler relationships to improve the stability of substantially closed, low-maintenance aquaria.

Rgrmill says: Let's take a brief break now and see if there are questions. After that I'll take up a few things that we can do to balance our tanks and provide for better conditions or less work.

BobJones raises his hand

Rgrmill asks: BobJones?

BobJones says: So to promote Algae growth, ammonia must be present.

Rgrmill says: Ammonia is a much more efficient source of nitrogen for most aquatic plants. In some cases (euglena) it is well established that *only* ammonia can be used. Terrestrial plants tend more to using nitrate.

Rgrmill says: I have read some statements in the technical literature that aquatic plants will use nitrate *only* when they are stressed into it by a complete lack of ammonia.

BobJones says: Thanks

Brianl raises his hand.

Rgrmill asks: Brianl?

Brianl says: So to promote algae growth we want nutrients to be in the water...but aquarists are always encouraged to do frequent water changes... Do you think it would be best to cut down on water changes for fish that are herbivorous? and how do we best promote algae growth in terms of lighting in a mbuna tank?

Rgrmill says: Water changes are a good way to keep a system stable and to maintain acceptable water quality. Water changes should be reduced only if the community of organisms in the tank is built up first and gradually. No sudden changes. The growth of algae (or biofilm, or aufuwchs) for mbuna is an interesting subject and we might get into it more later.

Brianl says: I'd be very interested in that...thanks.

Rgrmill asks: Are we ready to go on?

BobJones says: Sure

Rgrmill says: Ok

Rgrmill says: I'll give three examples of aquaria that illustrate varying degrees of environmental balance in their setup and maintenance.

Rgrmill says: The extreme, no-balance case is best illustrated by your basic Betta jar. The fish is fed daily and the jar is emptied and refilled every day or so.

Rgrmill says: Betta's (but nothing else) are easily maintained this way. There are no balancing elements in the setup, and the maintenance load (on a per-gallon basis) is extremely high.

Rgrmill says: A more moderate example might have enough light to view fish and to support some algae and slow growing plants; it has a gravel substrate and an undergravel filter with circulation and aeration provided by an air pump.

Rgrmill says: The tank is fed two or three times daily and supports a population of aerobic bacteria, diatoms and some green algae, a few fish and some snails. There may also be a planarian here and there and a few other, often problematic organisms like blue-green algae.

Rgrmill says: This is a very standard sort of system and it can successfully support most of the fish kept in the hobby.

Rgrmill says: Aside from daily feeding, tank maintenance involves periodic water changes, gravel vacuuming and glass scraping.

Rgrmill says: This system is stable partly because the bacteria, snails and what little algae is present provide for some partial nutrient processing but largely because the system is kept open by repeated water changes and changes and gravel cleaning.

Rgrmill says: If you forget to turn the light on, skip a water change or two, or forget to vacuum the gravel, then problems like fish diseases, or blue green algae blooms can take hold. If the light level is increased then nuisance algae may become a huge problem.

Rgrmill says: In 'Dynamic Aquaria' Adey and Loveland describe several tanks at the 'environmental' extreme. I'll only cover one of those.

Rgrmill says: The tank is a 70 gallon tank setup to simulate (roughly) conditions in an African pond.

Rgrmill says: It was started with 25 inches of cichlids (Tilapia mariae, Melanochromis auratus and Pseudotropheus tropheups) and 4 inches of catfish (Arius berneyi). It was also rather heavily planted, with 5 species of aquatic plants.

Rgrmill says: The tank was fed 0.3 grams/day of commercial flake food. I probably feed about twice that amount on a per-gallon basis.

Rgrmill says: Two adult M. auratus and a large number of fry were lost to predation, but the M. auratus and P. tropheops both bred successfully. After 3 years the tank had 40 inches of cichlids and 8 inches of catfish.

Rgrmill says: The tank water was circulated through a brightly lit tank holding screens supporting an algae population. That was the tank's only filtration. The algae screens were periodically cleaned, but there were no water changes.

Rgrmill says: Water was added to make up for evaporation.

Rgrmill says: The authors report a partial census of organisms with established populations in the tank. They reported 42 different species of blue-green algae, algae, plants, protozoans, nematodes, rotifers, mollusks, cope rotifers, molluscs, copepods, bryozoans and fish.

Rgrmill says: The algae, while present, weren't noticeable. The census did not include bacteria or plankton.

Rgrmill says: Nitrate concentrations varied from 0.6 mg/l to 2.5 mg/l as nitrate. A lot of us drink water that is more polluted then that.

Rgrmill says: Adey and Loveland had more resources at their disposal than most of us could muster. A tank like their 'African pond' is probably out of the question for most of us.

Rgrmill asks: So what - realistically - can we change to make effective use of environmental relationships in aquaria?

Rgrmill says: I've been reading and experimenting with tanks for several years, looking for working solutions. My experiments are never-ending, but I think there are some things we can do.

Rgrmill says: The goal is to provide the aquarium with stability and high water quality, and to do so with acceptable maintenance levels.

Rgrmill says: If a simple tank is suffering problems with poor water quality or stability, then its necessary to open the system - to do more work in exchange for better quality and stability.

Rgrmill says: This means more cleaning, more frequent and/or larger water changes, and better circulation.

Rgrmill says: If a tank is well maintained but water quality isn't good or the required maintenance is too great to be justified by the water quality, then it's time to add more diversity to the system.

Rgrmill says: The simplest step toward a more diverse system is simply to shut down a UGF if you have one.

Rgrmill says: Under gravel filters pull water through the substrate, keeping your tank and substrate rather homogeneously aerated. Without water movement through the substrate, it can start acting more like an aquatic soil, thus supporting a larger and more diverse population of benthic organisms than might otherwise be possible.

Rgrmill says: You might try adding some fine sand to the substrate to get a more soil-like consistency. You may also try to 'seed' benthic organisms into the tank from a clean natural waterway.

Rgrmill says: If there's detritus in the tank, add detritivores, usually snails. If there's algae in the tank, add herbivores - usually algae eating fish.

Rgrmill says: If those elements are already present, then increase the light to provide at least 2 watts per gallon of fluorescent light. I'd suggest more. Then add aquatic plants.

Rgrmill says: If algae become a nuisance, then add different kinds of herbivores. Usually this might just be a different kind of herbivorous fish.

Rgrmill says: I do mean a *different kind* of herbivore, rather than more of the kind that are already present. My experience is that herbivores are fairly selective. Just because one eats algae doesn't mean it will eat *all* algae.

Rgrmill says: You might have three kinds of nuisance algae, and need 3 kinds of herbivores to control it.

Rgrmill says: The last diversification step that I've worked with enough to recommend is to circulate water from your system through an entirely different setup where you can support biological conditions that couldn't otherwise exist in your tank.

Rgrmill says: This provides for a much more complex environment than could otherwise be achieved.

Rgrmill says: Reef keepers use "refugia" to support plankton populations. Adey and Loveland use interconnected tanks to (e.g.) allow reefs and back reef lagoons to coexist in the same system. This isn't a new idea.

Rgrmill says: In 'Advanced Aquarist Guide' (published in 1969) Ghadially described the use of a 'circulating range' to support daphnia in tanks connected to other aquaria, including a community tank and breeding facilities.

Rgrmill says: This is essentially identical to the refugia and was supposed to provide better water quality, low maintenance demands and live food.

Rgrmill says: Ed Tomlinson's central plant filter (described in Ed's Garage) and the 'algal scrubber' touted by Adey and Loveland are different manifestations of the same idea.

Rgrmill says: I use a similar setup, modeled after a swamp. I circulate water from an aquarium into a tank with mostly emerged vegetation and a thick substrate with lots of organic matter.

Rgrmill says: The water circulates rather slowly and is pumped back to the aquarium from below the soil. This provides for nitrogen uptake by the plants and for denitrification and other anaerobic processes in the soil - all processes that probably won't operate in an aquarium.

Rgrmill says: The most important requirement in adding environmental balance to an aquarium is self control.

Rgrmill says: Aquarists must thoroughly control the impulse to overload an aquarium with too many fish, or inappropriate combinations of fish.

Rgrmill says: They must work patiently to allow changes to develop their full effect before additional changes are made. Biological systems aren't established and fully functional overnight. A system that might otherwise work can be completely unstable if changes are introduced too abruptly.

Rgrmill says: That concludes the talk. I'm open to questions.

BobJones raises his hand

Rgrmill asks: BobJones?

BobJones asks: How long (approx) does it take for a biological system to be established? In a 29 gallon??

Rgrmill says: That's got to be pretty variable, Bob. In the tanks I'm experimenting with now, I generally give 2-3 weeks for any change to come to full effect. In some cases I see effects still developing for several months after changes are made.

Rgrmill says: In a 29, the rates would probably be about the same.

Thurin raises his hand.

Rgrmill asks: Yes Thurin?

Thurin asks: Is tons of algae bad for a tank?

Rgrmill says: No, not necessarily.

Thurin nods.

Rgrmill says: Especially if there's things eating the algae.

Brianl raises his hand.

Rgrmill asks: Yes Brianl?

Brianl says: What is the best way to promote algae growth in a mbuna tank? especially in terms of lighting.

Rgrmill says: Obviously, very bright lighting, with a fairly natural photoperiod. Erratic (short periods of light and dark) can kill algae. Plant keepers do that to keep algae under control. Use at least 2 watts of standard fluorescent per gallon of tank capacity.

Rgrmill says: Another feature that might be *very* important is to start with rocks that already have an established community on them. My experience is that rocks with natural communities (from streams or lakes) are very different from what you can get starting with a sterile rock.

Brianl asks: should any nutrients be added?

Rgrmill says: I don't suggest adding fertilizers, Brianl. I'm using trace elements in some of my planted tanks, and I get better results with bright light.

Juanmi raises his hand.

Rgrmill asks: Juanmi?

JuanMi says: So it could be beneficial for a system to promote anaerobic conditions, from that point of view, what is your opinion about gravel vacuuming

Richardb nods his head in understanding.

Rgrmill says: If you use a UGF, you need to vacuum the gravel. If you don't, then you should only use the vacuum to lift detritus off the surface of the gravel. The preferred action is to have greeblies living in the substrate so that there aren't any wastes there.

JuanMi says: Thanks

Brianl raises his hand.

Rgrmill asks: Yes Brianl?

Brianl asks: Loiselle seems to feel that the bacteria associated with bloat are anaerobic and that gravel substrates may not be the best idea. Do you agree with this?

Brianl says: I'm thinking of stripping my gravel and adding sand. A very fine layer

Rgrmill says: Many pathogenic bacteria are anaerobes. That doesn't mean that the substrate harbors or in any way fosters those diseases in the fish. Personally, I don't like gravel substrates. I like it to be more fine grained.

BobJones says: Buy pool sand, it's much cheaper and will be sufficient

Brianl says: I use play sand bob, cheap, clean...good stuff

Thurin raises his hand.

Rgrmill asks: Thurin?

Thurin asks: If there are no herbivores to consume algae, is its rampant growth detrimental to the life of the tank?

Rgrmill says: If there are no herbivores, then you have to harvest the algae by hand. I don't envision ever letting algae grow unchecked.

Brianl raises his hand.

Rgrmill asks: Yes Brianl?

Brianl asks: When you mentioned aufuwch earlier what were you going to add??

Brianl asks: Do you have any suggestions for creating aufuwchs?

Rgrmill says: Brainl, There are some features of biofilms (aufwuchs) that I've come across in technical literature that make it seem like growing biofilms and growing algae aren't necessarily the same thing.

Brianl asks: I'd imagine it is much more complicated...any ideas?

Rgrmill says: First is that biofilms are not just algae; they are a community of algae (different types) some fungus and bacteria bound together in a carbohydrate slime. The biofilm will develop within minutes on anything submerged in a natural water body.

Rgrmill says: Second is that biofilms are different when grown on different surfaces; wood grows a film that is different from what grows on rock, which may be different from what grows on a different kind of rock.

Rgrmill says: And last is that the complex communities that appear to form biofilms are probably best established using natural materials, rather than trying to grow them on sterile surfaces.

Brianl asks: and also more complex organisms like larger nematodes and crustaceans, right?

Rgrmill says: The larger organisms found with biofilms would be grazing on the biofilms.

Brianl asks: right, but in an aquarium they'd have to be added, right?

Rgrmill says: I think growing biofilms for your mbuna might be a great application for a refugia. Put rocks from a stream or lake into a very brightly lit tank with no fish, circulate water from you aquarium into the tank an into the tank and let things grow. Now and then, take rocks from the refugia and put them in your tank, and replace them with grazed rocks from your tank.

Brianl says: very interesting idea, there's always the fear of bringing in parasites though.

Rgrmill says: I have a lot less fear of that than most people. You can keep your starting stock isolated for weeks before connecting it to the fish tank. That should clear most any obligate fish pathogens or parasites.

Rgrmill says: Fast growing, Brianl. Adey and Loveland claim that harvesting algae of the substrate (as you would if you cycled rocks back to the mbuna tank) will favor a community of fast-growing productive algae.

Thurin raises his hand.

Rgrmill asks: Thurin?

Thurin asks: Ok, so if the algae is allowed to grow unchecked, will it be harmful to the rest of the tank? Live plants, bacteria, fish?

Rgrmill says: Yes Thurin, it will be harmful if allowed to grow unchecked.

acB raises her hand.

Rgrmill asks: acB?

acB asks: how do you circulate water from the main tank to the refugia and back without contaminating the main tank, if you are using the refugia to isolate any parasites from natural rock?

Rgrmill says: You isolate the refugia for a period of time before its connected, so that anything that is necessarily a parasite will die and be gone before you start circulating water through the tank.

acB says: thanks

Juanmi raises his hand.

Rgrmill asks: Yes JuanMi?

JuanMi says: But, fish parasites wont find shelter in the anaerobic media of the refugia once the tanks are connected? from the fish tank to the refuge, not the other way around.

Rgrmill says: Most parasites (I think) will be aerobic critters, so they won't be harbored by an anaerobic media. Obligate anaerobic bacteria would die quickly in the aerobic state of the fish tank; the caution there there is that anaerobic pathogens have been found living in microscopic specks of organic matter. For those pathogens, there is nothing you can do. They are already in the system, and they're going to be there even if you have no large anaerobic environment in the system.

JuanMi says: I had an experience, I was using a central filtration with algae in the central filter, the water had great parameters, but the fish kept dying one after the other, one each week, I tough parasites were living in the piping, happy with the great water conditions, no drug treatment was good enough. I quitted central filtration one day after two years and deaths stopped the same day.

Rgrmill says: One of the long-standing complaints about central filtration is its ability to communicate diseases from hosts to victims in entirely different parts of the system. Without central filtration the parasite from the host would not get access to the victim.

Rgrmill says: I have never seen that in action, and Ed said he hadn't either, but because of those complaints, I wouldn't use a circulating system to connect two tanks with fish in them, unless there were a barrier between t were a barrier between them that I though could prevent movement of parasites or diseases.

Rgrmill says: For my purposes, Juan I take a different approach. Keep the fish unstressed and it won't be subject to diseases.

JuanMi says: That can not happen Roger. In my opinion you can't keep cichlids in aquaria unstressed all the time.

Brianl asks: maybe uv sterilizer inline?

Rgrmill says: The fish has to have a functioning immune system. I will *never* maintain a sterile tank.

Juanmi nods his head in understanding.

JuanMi says: My fish were breeding and doing great, just dying one in a row

Brianl asks: dying of what Juan?

JuanMi says: from parasites, living in the central filtration system

Dev says: I don't see how a central filter harbors any more parasites or harmful bacteria than a normal filter does, if the central undergoes regular cleaning like any filter. The main drawback is that *should* a parasite en enter a central system, it has the potential to do a lot more damage than in an isolated tank.

JuanMi says: I am talking by experience Dev, terrible experience, almost drove me out of the hobby. It is also true that I keep many wild fish, although I quarantine with care.

Apistogramma says: an advantage to a centralized filter system is the ability to use anti-parasite technologies like a micron filter or a UV light and treat all of the water with one unit, rather than a separate unit for each separate unit for each tank.

Juanmi nods his head in understanding.

Rgrmill says: Of course, a UV filter would be the opposite of a good environmental influence.

JuanMi says: Like in public aquariums, expensive equipment yes

AquaBoy says: In a pet store near me they have these two gigantic filters that are the size of a small room, they have many gizmos on them that I have no idea what they do, I'm pretty sure the two filters filter all the tank filter in the store (its a very big store).

Dev says: yes Juan. I see your dilemma. I think wild fish aren't good candidates for a central system. Even well-acclimated wilds will hold parasites in them that can wreak havoc on tank-raised fish not used to fighting off the nasties.

Apistogramma says: But, Dev, if Juan used a micron sleeve in a pre or post filter, the only parasites that would get through would be protozoan.. most healthy fish can fight those off. It is when the fish stress that protozoans do the most damage.

JuanMi says: Unfortunately, cichlids do stress in aquariums, no matter how large they are

Dev says: true, but that is why the central is a bad idea in this case. It remains a time-bomb, until you stress the fish (like missing a water change or two)

Brianl says: good point Dev

Brianl says: Why not just treat the wild fish in quarantine with a broad spectrum anti parasitic. Something like Paragon II mixed in their food.

Apistogramma says: that is what I would do, but also use methods in the filter to catch 'accidents'

Juanmi nods his head in understanding.

Apistogramma says: central filtration is good for the fish breeder who has a lot of fry that need to be grown but cannot be mixed..... It allows a person to have many tanks of many fish that basically acts as one big tank... basically acts as one big tank...

Dev nods his head in understanding.

Apistogramma says: I would not use central filtration for breeders though....

Juanmi nods his head in understanding. Neither for aquarium stores

Brianl says: There are a lot of horror stories out there.. but when you get into big tanks and lots of gallons the central system is by far the most economical.

JuanMi says: It is Brian, also the most deadly

Brianl says: I agree, same gamble, higher stakes. I know the cichlid exchange has individual filters in each tank...that surprised me.

Brianl says: perhaps dealing with so many wild fish they've run into the same problems you guys brought up.

Apistogramma says: if the system is set up with checks and balances... like being able to cut a tank out of the system for medication or quarantine... then they can be very useful...... Especially for stores.

Rgrmill says: Its' the way it goes, Ted.

Cap says: I don't get something. Isn't saying that you wouldn't connect two tanks with fish kind of like saying "I'd never own a 180 gallon fish tank. Instead, I'd own two separate 90 gallon tanks."

Rgrmill says: Cap, it may be; except that in two connected tanks I'm probably supporting populations of fish that I would never put together in a 180.

Brianl asks: About those sealed glass globes you mentioned earlier...the captive systems? I've always wondered how they could work, since they are not without connection to the outside environment. Too much light and the algae bloom and then die from lack of nutrients...too little and the herbivores die... Same connection with temperature and metabolic rate and waste production. can these systems work Roger?

Rgrmill says: The systems are for sale, Brianl. I think they are extremely expensive, but have a warranty to work for a minimum period. One of them has a 3-year warranty (this is second hand info).

Brianl asks: I know they're for sale but that doesn't mean they work...what I said about temp and light is correct right?

Rgrmill says: Two much light probably won't be a problem. Too little light will kill the system for lack of calories.

Brianl says: the systems I've seen have had some kind of macro algae looking thing and several brine shrimp...I seem to recall that brine shrimp really don't live that long...

Rgrmill says: Brianl, the systems would depend on the shrimp reproducing, and the macroalgae would be a poor food source. The shrimp are phytoplankton feeders.

Brianl says: Roger I assumed the brine shrimp are not breeding...that only one sex is placed in the globe.

Brianl says: I know the brine shrimp are phytoplankton feeders that's why I question the whole thing.

JuanMi says: Roger, it was certainly a great talk, leaves a lot to think about

Rgrmill says: Thank you Juan.

Richardb says: I have to leave folks. Thanks for a wonderful talk Roger, I look forward to reading the transcript again. Bye.

Richardb applauds Rgrmill for his excellent talk.

Sabrina applauds Rgrmill also

JuanMi applauds Roger

BobJones applauds Roger

Brianl says: Great talk Roger


Miller, Roger. (May 27, 1996). "Environmental Balance in the Freshwater Aquarium". Cichlid Room Companion. Retrieved on May 21, 2019, from: