Changing Gravel, How Long to wait.

[John_K]

I'm in the process of changing the gravel in my 55g and have completed 1/2 of the tank. How long should I wait for the bacteria to eastablish itself before doing the remaining 1/2.

[MP]

Unless your main filter is UGF/RUGF OR your filter can hardly handle the bioload OR your tank is not really mature yet, you can change all gravel in one shot.

With UGFs/RUGFs, marginally effective biofilters or in a case of a relatively new tank, I'd wait for, at least, about 3-4 weeks.

Naturally, you can always play it safe if you wish. Less room for an error.

[Water Witch]

Ditto.

If you have any doubts, feed smaller than normal meals for the first week after or skip feeding entirely. A reduction in bacteria bed can be dealt with via a reduction in waste production and your fingers directly control what comes out of the fish since they provide what goes in.