The piece of wood is a compromise - like so many things in life. There is no arguing that it releases tannins in the water, which tropheus are not used to in their natural environment. That could cause problems and needs close monitoring, but I doubt it is the reason for my current misery (which I believe is a bacteria infection brought on by introducing the multies - consistent with the suddenness disaster struck). Problems stemming from the wood should have started earlier, if the tannins were causing an immediate problem for the tropheus, or they should come on slowly if the problem was cumulative, meaning if tannins or their metabolic products would built up in the tropheus over time. I have not seen any evidence of this, and I am doing my best to keep the concentration of tannins at a minimum through daily 10% water changes via an automatic water change system. There is some browning of the water, but not excessively so. Measurable water parameters - pH and gH - are identical to my tap water, so it's not correct to say the wood softens my water. It might try to, but I am not giving it the chance
The risk associated with the wood in my opinion is outweighed by many advantages:
- It is shaped like an upside-down rock pile, meaning it has a comparatively small base and a huge upper part close to the lamps. This promotes fantastic algae growth on which the tropheus graze.
- It reaches all the way to the water surface, which would be difficult to achieve with a stable rock setup, and especially the gobies like to perch up there.
- It provides superb cover for fry, which I would have difficulty matching with any rock setup.
- It looks good and is unusual - of no consequence to the tropheus, but matters to me for purely selfish reasons.
As an aside, the tank is also close to an east facing window, and gets lots of morning sun, which means plenty of algae growth, but no temperature problems even in summer.
Regarding the food, for my first 20 years in the hobby I fed almost exclusively flake food, and like you, I had good success with it, so it's hard to argue against that. However, when I got into frontosa I went off flake food in a big way. Many frontosa keepers have troubles caused by frontosa eating from the surface. It is not a natural behavior for them, and if they do it, they can gobble up air which leads to digestive problems. Feeding them sinking pellets completely eliminates this risk. Sinking pellets are also a lot more practical to feed in tanks that are filtered via a sump system that's fed through overflows creating a huge surface current like my 240G frontosa setup. That's what caused me to abandon flake food, and I saw no reason to go back when I got the tropheus. I don't think I ever heard about tropheus developing problems from surface feeding, but I believe it is no more natural for them than for frontosa. So I think it is best to be avoided.
I am not familiar with Jehmco food, although Jehmco seems to have an excellent reputation. Ken's food is super cheap, and I stock up on his flakes at the OCA Extravaganza to feed my guppies and other life bearers. I have recently heard from a number of people who use his food extensively and complain about the quality. Allegedly it colors the water more and fouls it quicker than other more expensive foods. Not personal experience, but I heard that from several people now.
I totally agree with you that any food containing spirulina is preferable to the best food without spirulina. I am not sure which of Ken's spirulina flakes you feed, but I'd be reluctant to feed his 'Pure Spirulina Flakes' exclusively. It is 100% spirulina, and in their natural environment tropheus eat Aufwuchs, which of course is mostly algae, but not only algae. Ken's 'Premium Spirulina Flake' contains some spiruline, but you don't know how much. The same is true for Xtreme Cichlid Crumble. Comparing what they tell you about the ingredients, Xtreme appears better suited for tropheus than Ken's, since it is lower in protein and fat while higher in fiber:
Just out of curiosity, what did you not like about NLS? I think you would be the first person I talk to who has found anything to criticize about NLS other than its price!
Back to my current problem, I lost both the fish in the hospital tank and the one with the bulging eyes over night. Other than the eyes, there seemed to be nothing wrong with the latter fish yesterday, but this morning it lay dead on the bottom of the tank. This brings the total death toll up to five. The rest of the colony looks fine now. In fact, they are very active, and show as good coloration - lots of orange - as I have ever seen in them. I did another 50% water change and topped up salt again. I might do that for another few days and also keep the temperature up. I think I'll have to start feeding again tomorrow. By now they have scraped every tiny bit of algae off even the hardest to reach places on the backwall and the rocks and wood
Again, many thanks for your help and the exchange of information. It's always fascinating to compare notes about different people's approach to keeping fish!