well on my 55 that i have tried them, it has 2x150W lights over it one bulb is 14K the other 20K, and then 2X55w PC actinics. The flow is the return a koralia nano and koralia 2 in the tank. They never seem to excel, i do a 5gal water change every weekend or a 10 gal every other weekend. I am currently setting up a 10 gal with hob filter that i want to dedicate to ricordia and zoa's hence my original question.