Bioballs vs. LR

[chickenhawk]

Ok, so I've heard the ol' "replace your bioballs with LR to better your system" flung around the board quite a bit.

Here's a few questions:

Do you have to have some sort of light source for the LR if you do this? I was considering doing it, but there is no lighting for my sump.

Also, would it really make that much of a difference to switch to the LR?

Lastly, would it be ok to replace the filter medium in my whisper HOB in my 2.5 SW with LR (I kinda already did, the filter was heinous!). I also have LR in the tank as well.

Thanks for your help!

[blockamon]

Well, I'll take a shot:
1) No, you don't need light for live rock to act as a biological filter.
2) I personally don't think live rock should be used in a trickle-type filter. It might be a little better than bioballs, but the high oxygen environment would most likely cause the same nitrate problems. IMHO, live rock should only be used completely submerged. Also IMHO, any plain ceramic media would work as well (maybe better, since they are fabricated to have lots of pore area) in a filter.
3) If you have live rock in the tank at about 1 lbs/gal (pacific rock, ~2 lbs/gal caribean cultured), I don't see a compelling reason to use live rock in the filter. I would personally use a mechanical pre-filter and a bag of carbon/GFO.

[Reefkid 07]

I have taken out my bio balls lately and replaced them with crushed lr and some hard coral. Will this be good biological?

[Reefkid 07]

And what exactly does biological filtration benifit?

[blockamon]

Biological filtration is probably the most important in any tank, saltwater or freshwater. The primary fish waste is ammonia, which is extremely toxic. Aerobic bacteria in the biological filter (bioballs, live rock, etc.) convert the ammonia to nitrite (still toxic in freshwater, doesn't interract in salt water) and finally to nitrate. When using highly porous, submerged media (like live rock in a tank or filter), the interrior surfaces will be low in oxygen and begin growing anerobic bacteria. These bacteria convert the nitrate to nitrogen gas, which bubbles off.

In general, the aerobic bacteria work faster, which is why many people have nitrate problems. Nitrate can be somewhat controlled by water changes, but even that isn't a great way to get the super-low levels the some corals like. Some additional means of nitrate export is often required (unless you have lots and lots of live rock AND a low bioload) to get down low enough for some corals (like SPS) to be really happy. I personally use a denitrate filter (DIY) but others use a macroalgae refugium.