Live Rocks and Display Tanks

[Terrance]

Besides denitrification, what else does live rocks do? I also read that it breaks down organic waste. Solid or dissolved or both? That must be the "live" part of the rock breaking down the waste, correct?

The recommendation is to have 1-2 pounds per gallon. The more the better. Why so much? In FW, the main component is my filter sponge. If I put in more rocks, should I expect to go on longer without water changes? I'm thinking this relates to the first question. The breakdown of organic waste.

 

[Sniperhank]

Your live rock/sand are your filter. The more you have, there is more area for bacteria to live. I wouldn't take it as far as saying that you can go longer w/o water changes as the water changes are replacing the elements that were in the water that are absorbed over time by things like corals or removing waste from critters. The more LR you have the more your environment can handle in terms of bio-load. The 2 lbs mark is pretty much where you will not see any more added benefit from having more LR. When people talk about setting up fuges, one of the things people put in is live rock and sand, but if you are in the 1.5-2lbs of LR there will not be any noticed benefit. So you can pretty much avoid that and just add macro algae...but this is getting way more detailed than needed to answer your question.

 

[Terrance]

I like the details. So LR do not break down organic waste? Only for denitrification? I'm thinking that the organic waste breaks down into ammonia (LR will take care of that) and dissolved organics (skimmer takes care of this). Then you have algae to reduce both. Rely on mechanical filtration and siphoning to remove solid waste.

In FW, one small filter sponge leaves nitrate in the water. LR gets rid of the nitrate. Is that why there is so much live rocks in the tank?

If I could hold 1-2 pounds per gallon of live rocks in my sump, then I don't need live rocks in my display tank?

 

[jlaborce9]

Doesn't seem likely that you could fit that much in a sump but theoretically I think it makes sense. Id also like to know the answer to that because I like a more open look. If you just shove as much live rock as you can in your sump does that allow the more open look without any consequences? Assuming you still meet the lbs per gallon rule

 

[jwalsh]

I'm not sure about the fuge thing but live rock has the bacteria that turns the. Amonia into nitrite and from nitrite to nitrate so in a sense its a filter. Then you do pwc to get rid of the nitrate. There are other ways to get rid of trates I.e. activated carbon and skimming but I do a pwc every 10 days just to make sure everything is under control and replenish the micro nutrients that are absorbed by the organisms in my tank I.e magnesium calcium ect.

 

[Hondatek]

Whether the rock is in your sump or in your display it still works the same way since it's still in your system.

 

[mr_X]

of course you can have most of the live rock in the sump, if it fits. I have about 200 pounds in my display, and another 150 in my sump. All of it helps with filtration, And I don't want a giant pile of rock in my tank. I want lots of swimming room and room for coral colonies to grow.

Live rock has 2 types of bacteria (aerobic and anaerobic) One breaks down the ammonia to nitrite and then nitrate, and the other turns the nitrate to nitrogen gas.

 

[Terrance]

The less rocks I have in my DT, the easier it is to clean.
Waste will naturally slowly release ammo and dissolved organics. I'm assuming live rocks do not break down waste since nobody is mentioning it. LR will convert ammo to nitrate to gas. Skimmer collects the dissolved organics. LR and skimmer can't completely get rid of nitrate and dissolved waste, so we do water changes. Algae (chaeto) will help reduce both and prolong water changes.

We're all on the same page, right? LR do not break down waste. I'm thinking there is a bunch of LR in SW tanks (compared to a FW filter sponge) because there needs to be more areas for anaerobic bacteria to live.

 

[mr_X]

Waste will break down on it's own. It will dissolve over time in the water. Think about leaving a cocktail shrimp in the tank to start a cycle. Eventually it disappears.

It's not that salt water needs more are for bacteria, It's that we found that live rock can be a filter. You are the one who needs to tend to the chunks of food sitting on the bottom. whether it's manually removing it, or purchasing a fish or crab to eat it. If you want a healthy tank, that is.

 

[Terrance]

Yeah live rocks is the biological filter. It just seems very odd to see LR occupying ~1/3 of the DT (1-2 pounds per gallon) compared to my filter sponges in my FW tank. If I took out all of my sponges and placed them in my FW DT, then less than 1/4 of the tank would be occupied with sponges. My only reasoning is we need more LR to house more anaerobic bacteria, which doesn't happen in FW tank (besides the use of pond matrix).

 

[Sniperhank]

If you have a good layout, it doesn't take up much space is taken up at all. I have roughly 50 lbs in my 36 gal and I still have lots of room. I have rearranged several times to meet my needs. Doesn't stop us from wanting larger tanks though!

 

[mr_X]

You have to watch though- not all rock is created equal. The lighter, more porous stuff takes up a lot more space.