I have a 1 month old 40g breeder with a 20l refugium. Right now the only fish are a pair of clowns. It has about 10hermits and 1 decorator crab. The lights are 6x39w t5ho nova extreme pro fixture. Am, trite, trate, and phos are 0, but the tank is barely stocked so that is normal.
Then I have a 75g, with only a HOB filter. Changed about 25g of water 2 weeks ago. Fish are a small blue tang, yellow tang, kole tang, 1 chromis, a pair of maroon clowns, and a snowflake eel. Lights are pc and a t8 bulb. Am, trite is at 0. Trates are always between 5-20 and phos .25 or less.
The 40g is going to become most an SPS tank, so dissolved organics can be used to feed the corals, and I'm only going to get 2, maybe 3 more fish.
The 75g is at it's limit with fish, and the blue tang is going back to the store with it reaches 4-5 inches.