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add to the bioload, effectively reduce the bioload, or work out to be fairly neutral when it comes to waste output?

For animals, the entire universe has been neatly divided into things to (a) mate with, (b) eat, (c) run away from, and (d) rocks. - Terry Pratchett

bioload = created by waste producing organisms.
Liverock itself (and its occasional invert inhabitants) don't contribute much in terms of bioload.

What liverock DOES add is beneficial bacteria and a fantastic surface area on which bacteria essential to the nitrogen cycle can colonise. Most reef systems use liverock as the primary biological filter. Tanks with live rock can support more bioload than tanks without, and also increase the diversity of life in the aquarium. It's full of goodies like copepods and bristle worms that provide a food source for other organisms and clean up detritus and uneaten food.

yup, I'm good with that What I'm trying to figure out is if the quantity of LR has direct bearing on stocking levels (read: more LR = more fish) much like quantity of plants or filter media/turnover in FW, and if there is a break point at which it/creatures on it/etc outputs more waste than it consumes or if that is the way that it works regardless of quantity. I'm assuming nitrate will be occurring and that it isn't a magic wand etc.

I guess what I'm asking is how does it compare to FW in its impact on the water quality, on par with a pleco, a handful of shrimp, or some plants?



For animals, the entire universe has been neatly divided into things to (a) mate with, (b) eat, (c) run away from, and (d) rocks. - Terry Pratchett

Aaah I get you now.

There isnt a breaking point at which it will create more waste than it cleans up, and I would say it has a greater impact on water quality for marines than plants do for fresh water. The organisms on the live rock (critters, corals etc) are negligable in terms of bioload, but the effect of the extra bacteria and surface area on nitrate reduction is significant.

For reef tanks the general rule is a lb per gallon (or 0.5kg per gallon if you prefer), tanks with less than this convert nitrates sub-optimally and hence cant support higher stocking densities.
There is no benefit to adding more liverock than a lb per gal IMO, not because of the critters on the rock, but because it impedes flow in the tank. Obviously poorer flow = dead spots which will adversely affect your nitrates.

Adding more liverock is comparable to adding a large biological filter, so I would say you can stock more densely in systems with plenty of LR (or at least reduce the frequency of your water changes).

*Hannah - rambling in place of James*

Basically the LR is comparable to things like bioballs and biowheels in FW tanks. And these are used as well in SW tanks. So they have large surface areas for bacteria growth for the cycle, up to the nitrates. Just as FW does. If you are looking for the conversion of nitrates however, you will need to look into other means. Such as a deep sand bed, or a cryptic refugium. These are just a couple of the ways. Another is a large refugium with plants, such as cheto or magro algae.

As for increasing the stock, well that can be done if you are planning on doing greater water changes and such, just as you would with a FW tank. However, if your cryptic refugium, or deep sand bed are large enough, you should be fine. Most people that want to increase their stock in a specific tank, usually end up with equal to larger refugium/filters than the actual tank. For example, I have a friend that has a 400 gal reef and fish tank. About a third of the tank is LR. His refugiums consist of a 250 gal cryptic tank, a 150 gal deep sand bed tank, and a 125 gal high flow refugium plant and small critter tank. In the end, his refugiums equal 575 gals, compared to the actual 400 gal tank. And he has not done any water changes in the tank for now over 6 years. Just water replacements from his 750 gal RO water holding tank.

So basically, yes you can over stock your tank. But, you will need to increase your refugiums and their sizes to do it. The addition of more LR will just help in the ammonia and nitrite levels of an overstocked tank, not the nitrate levels.

As for adding to the bioload, the LR does this only at the initial placement. And thus is the reason you should "cure" even LR you have purchased newly. As these creatures are very small on the LR, as is the bacteria as well, you will have some die off during the trip home. So you should always "cure" all your LR before placing it in the tank.

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