When eggs develop heads and tails and can move around a bit, they don't need tumbled any more. When I strip Vics at 10 days and Malawis at 2 weeks, I just put them in a a container of water with airation, and they're fine. The airation might not even be necessary. At 2 weeks, most Vics are almost free swimming, if not all the way free swimming. No need to tumble.