question!

[amp7594]

when should i refill the water to the top and when should i add the sponge filter

[1fish2fish]

Answers will vary. I like to begin slowly adding water as soon as the fry are free swimming, once it reaches the top start daily water changes.

I don't put a sponge filter in my spawning tank and when I put it in growout (usually about 1 month old) I keep it very very low until I'm sure the fry are big enough to not get caught in the current.

[vilmarisv]

I too start adding water as soon as they are free swimming, about 25% each day until the tank is full and then do water changes every other day until they are 2 weeks old. Once they are two weeks I start with the daily water changes.
I don't do daily 100% water changes because a lot of my fry would die when so young even if the water was aged and the same temp.
I add the sponge filter also when they are free swimming at a very slow flow, then increase as the fry get older but never at full power.