[mr_lock02]

I have a quick question about underneath my tank. I heard somewhere that the bioballs are a place where a lot of nitrates come from. So would it be better to replace the bio balls with some live rock? Maybe place a light under there. Would I add sand in my sump area? Any little critters down there? I dont know its just something I heard.

[CSeaSee]

You are correct. Bioballs frequently become a source of nitrates. LR is a better alternative, but you don't necessarily need a light. Some people add a DSB to their sump, but that's probably another topic.

[Poseidon]

Hi Mr Lock, yes I would replace bioballs with live rock, and some macro algae.

[leebca]

Another area of confusion that has been blown way out of proportion! The ol' argument about 'nitrate factories.' Thanks for posting this!

It seems people don't understand what is happening. There is no good nor bad in what is happening. Mother Nature doesn't make errors. It is a matter of what the aquarists wants to accomplish and what path is followed towards that accomplishment.

Live rock does many things: What is Live Rock, Anyway?

It can and does:
1. nitrification
2. denitrification
3. bring benthic creatures with it
4. bring many lifeforms with it

On the other hand, bio-balls do the following:
1. nitrification

Bio-balls got its 'bad rap' since it can only perform nitrification. These are the bacteria that convert ammonia wastes to nitrites and then nitrites to nitrates. Bio-balls change the poisons in the water to a fish-harmless compound -- nitrates. This is a good thing -- for the marine fishes.

But if the aquarist needs to reduce nitrates by other means than water changes (that is, if operating a reef aquarium with nitrate-sensitive marine life) then denitrification -- the changing of nitrates to nitrogen gas and other compounds -- OR other means of removing nitrates is needed.

If you want to add a light to the sump, and your point is to reduce nitrates, then you might as well put macro algae into the sump and let that remove the nitrates and leave the bio-balls alone. If you're interested in denitrification, then you want to pursue other options, one of which is putting in live rock. If you want to start growing things in your sump (other than algae) and turn your sump into a refugium, then adding live rock is one way of doing that.

Established bio-balls biological filters are so efficient at nitrification that the replacement should be slow over a period of many weeks to allow the live rock to pick up the slack and provide sufficient nitrification.