Rock for filtration

[SCFatz]

I read this a lot...well I read a lot period and this comes up a lot.

Heck I may have even asked this before,but why do people believe that live rock helps in the filtration department?I just can't get my head around the idea.

What if anything does it filter out of the water?I know it provides surface area for benificial bacteria,but that same bacteria would eventually develope on the substrate and filter media in a FO tank would it not?The bacteria population is dependent on the bioload,not the amount of rock it has to live on imo.

But there is this standard recommendation of 1.5/2 pounds per gallon but just don't see why that is....don't get me wrong I like the stuff and I'll buy more when I run across cool pieces...but does it "filter" my water?...I'm having a hard time with that one.

The one thing I have seen and this seems to have a bit of controversy attached to it is this:

The more rock you have the more pores you have,the more pores you have the more areas for anerobic conditions to develope.Its in the anerobic areas that some people believe that nitrate consuming bacteria develope...hence nitrate is consumed and nitrogen gas will leave the tank as a bubble.
I have also seen this refered to as the 3rd stage denitrofication (I think thats it lol)...anywho...not everyone believes this to be the case.

Anyone feel like driving this through my thick skull??I'm up for a good discussion on it actually but I'm off to work soon so I'll reply in the morning.

Filtration?Just surface area?Just pretty?Denitrofication?

[SCFatz]

I had no idea this would such a hot topic

[BillyZ]

Well you pretty much have the theory correct except for one small detail. An anaerobic area is a place with little to no available oxygen. In order to achieve an anaerobic area there needs to be little to no water movement because with water comes oxygen. This is what happens in a deep sand bed and on your LR deep within the rock itself. So why so much LR? Well, how do you efficiently filter a large volume of water if your filter, in order to "work", can't have a lot of water flow?

You make it bigger.


With a large volume of LR, you have a large amount of anaerobic areas. Each area only processes a small amount of water in a day so in order to handle your tank's daily bioload you want as many of these anaerobic areas as you can.

Did that help?

[SCFatz]

Thanks for the reply Bill.

It seems its safe to say that you agree with the anaerobic/denitrofication side of the reasoning.Cool.
IYO does that equal nitrate consumption?

That seems to be the "hot button" point here...will enough live rock help keep nitrate levels down,even if just a little...

[BillyZ]

will enough live rock help keep nitrate levels down,even if just a little...

typically Yes.

but wether or not it will help keep them down is a factor of your tank and your tank alone. Your bioload, the rock density, water flow, maintenance and feeding habbits etc can all contribute to wether or not your tank will have a net gain of nitrates or not. This is why a lot of SW reefers will even go so far as to have a large sump with a mass amount of LR rubble to give them room for even more LR.

HTH!

[SeeDemTails]

Rock helps keep a tanks water perfect....im no scientist so other than the reasons above I couldnt tell you, but my params dont lie....LR is key to a successful reef tank IMO.

[BillyZ]

I forgot another point I wanted to mention. I have always strived for a natural system in my tanks. One of the most important features to running a natural system is a diversified stock of life. The more LR and LS you have in your system the more room there is for pods, worms, sponges, snails, algaes (good algaes) etc. The more of them and more diverse a selection of life forms in your tank the more likely it will be stable and also capable of recovering from fluctuation. Thats just my little theory on things anyway.

[patman3d]

Like it has been said before, you want a good bacteria population.

Consider Live rock as apartment complexes. You can fit lots of bacteria (and other critters) into these 'homes'

Now consider 1 story homes in the same area... You can fit a lot of bacteria there but, nowhere near what you can when using LR in addition.

I know it's a little crude, but that's how I somewhat understood it to be

[lando]

NO3 reduction is a product of several variables. You are correct in the fact that LR (or any other bilological filtration media) does reduce NO3 by providing an area for benifical bactera to grow. The more, the better, and LR IS the best media due to its enormous surface area (LR is very porous). Feeding amount and schedule, as well as bioload all effect NO3. IMO, there is no perfect ecosystem in a home aquarium, regardless of size. They all still rely on us as a major form of nutrient export via water changes.

[abnmojo]

I love this board!!!!!

I guess about 20 years ago some german guy found that if you put a kick butt protien skimmer on a fish tank with nothing else for filtration at all, but had a LOT of live rock in there, you didn't really need anything else. They call this the 'berlin' method, you may have heard about it.

A lot has been learned in the past 20 years or so about live rock, but a lot more is still unknown. Geez, just look at the thread on deep sand beds on here!

From my own personal experience, and I have been doing this hobby since 1990, is that live rock makes a MUCH more stable system. The more live rock you have, the more stable it is. I have had hang on filters, protein skimmers, canister filters, sumps, UV sterilizers and NOTHING makes the tank more stable than a ton of live rock in there.

Just my personal experience tells me that you should have it in your tank even if you never want to have corals. It has so much 'good' going for it - and nothing bad. The fish love it to eat off of or hide in too. I think the fish (most are 'reef' fish, right?) need it from a mental stand point as well.

I have kept a 2 1/2 gallon nano tank with nothing but live rock for filtration since 2004. just an empty hang on filter for water movement and a couple of pounds of live rock. You tell me what is 'filtering' the water in there? The hang-on has a sponge to catch big nasties but other than that, the rock is the filter. My nano corals breed like crazy and my red-head goby is fat and happy, and still alive, two years later. If it works in that little tank, it only makes sense to work in a larger more heavily loaded system too.

At this point, I am done asking "how" and "why". I just know that live rock is good. very good. You can't ever really have too much of it.