If you're using a used filter that was established on another tank, when you move it to the 125 you will have a cycled tank.
----> It's the filters you're cycling, not the tank.
Your 125 will be cycled for the same bio-load you had in your 75. Since you're not adding a full stock list all at once you'll be fine. Do you have any other filters on your 75? That can easily remain the growout tank. Add an extra sponge or a few more hand fulls of bio (or whatever form yours comes in) to your established filter and when you have juvies in the 75 you can move the extra bio over to the 75 and have an instantly cycled tank for your juvies.
King dave is right, that fishless cycling allows you to build up a bigger colony, but this is really only necessary when you're adding a large amount of fish all at once. Since it sounds as if you're adding a few at a time, it won't make a difference. Just allow a couple weeks between additions to your big tank (2-4 fish at a time) and your filters will be able to adjust without any input from you. It might be helpful to reduce feedings for a few days after the new additions, but other than that, your filters will be fine and your fish will too.
:thumb:
----> It's the filters you're cycling, not the tank.
Your 125 will be cycled for the same bio-load you had in your 75. Since you're not adding a full stock list all at once you'll be fine. Do you have any other filters on your 75? That can easily remain the growout tank. Add an extra sponge or a few more hand fulls of bio (or whatever form yours comes in) to your established filter and when you have juvies in the 75 you can move the extra bio over to the 75 and have an instantly cycled tank for your juvies.
King dave is right, that fishless cycling allows you to build up a bigger colony, but this is really only necessary when you're adding a large amount of fish all at once. Since it sounds as if you're adding a few at a time, it won't make a difference. Just allow a couple weeks between additions to your big tank (2-4 fish at a time) and your filters will be able to adjust without any input from you. It might be helpful to reduce feedings for a few days after the new additions, but other than that, your filters will be fine and your fish will too.
:thumb:
