substrate

[Reefdude]

I'm having to move my 75 gallon this weekend so that the x-mas tree can have a space and since Its gonna be empty I wanna do a different substrate. I have sand now but I'm just not happy with it..I prefer crushed coral. Now my question is this..can I just place the crushed coral over the sand I have now or will it do bad things to the tank??? :-o

[Chris]

Crushed coral will eventually just all sink to the bottom. A good sand bed will consist of multiple grain sizes. You shouldn't have a problem adding it to the top although i'd be careful with how much you add at a time. I'd say no more than 1/2" layer per week... otherwise you risk killing off your sand bed fauna.

[Tim Marvin]

Actually the crushed coral is lighter and will stay at the top. At least that has been my experience. I would stick to the 1/2 inch method, that Chris mentioned, or at least no more than 3/4 inch. It will kill off some of the deeper critters if you add too much. You also need to consider the cucumber can be killed by crushed coral. They try to ingest it and it gets stuck, and cuts them up inside. Oh, and don't stir up your old sand too much it will put a lot of nasty bacteria in the water that can kill the fish.