Live rocks in sump

[Myka]

Originally Posted by reefme

Is it good idea to have live rocks in sump? Will it collecting debris?

Yes, it will collect detritus - even if you use a filter sock. You should remove the rock and clean the sump out every few months or whenever you see detritus building up.

Most reef tanks will have plenty enough nitrifying bacteria with even a small amount of live rock. The limiting factor is usually the anaerobic denitrifying bacteria that convert nitrate to nitrogen gas (and other "stuff"). These bacteria live within the rock and there needs to be a significant population to make a significant dent in the nitrate. For this reason, putting a bunch of live rock in the sump does have benefit. However, if the rock in the sump is allowed to collect detritus and isn't cleaned then the decaying detritus will add to the nitrate in the system, which makes the excess rock a moot point.