Any "scientific" proof live rock leaks N04/P04?

[Mark Taber]

As per topic, I hear people make the statement that rock leaks Nitrates and Phosphate over time but has there ever been any studies on this that someone can refer to?

 

[Reef man 89]

Following this for sure.

 

[redfishbluefish]

The proof is in the cure! Put rock into pristine clean fresh water that has zero N's and P's and voila, you get N's and P's showing up. It's called curing, where the death from within decays and leaches out, and we measure N's and P's to monitor this cure.

When the decaying has stopped or slowed, we see N's and P's topping out where a water change starts to lower these numbers. That's when we know the cure is done. You typically can cycle at the same time, but the cure usually takes longer.

 

[Reefiness]

I can provide my own experience from it.

A few years back i upgraded my tank after years of poor maintenance schedules and having nitrates and phosphates always running very high in the tank. The soft corals I had in the tank loved the high levels and grew like weeds so I didnt really have a problem with it. Hair algae began growing as well but I knew it was something I had to deal with because of the water parameters.

After I switched tanks an transferred all the rocks from my old set up I still found my nitrates and phosphates being elevated even though I had been really focusing on nutrient export, proper water change intervals, and having an oversized skimmer. After a while I began dosing vodka to keep my nitrates and phosphates under control. Got as high as 8ml a day to maintain a nitrate level of under 10. After a little while, I would start getting 0 nitrates coming up on my test meters so slowly began dialing back on the vodka I was dosing. After a few months of pulling back on the vodka dosing I was able to stop dosing vodka and still keep my nitrates under 5ppm without changing much else in the way I had been doing things since setting up the upgraded tank on day 1.

To me the only explanation I was able to come to was the rocks had absorbed a lot of the nitrates and phosphates back when they were constantly exposed to triple digit nitrates, and now that nitrate was slowly being pulled out of the rocks and back into the water.

I do not necessarily agree that rocks inherently release nitrates and phosphates, at least not in very noticeable quantities, but if they are able to absorb and release nitrates.

 

[Labridaedicted]

I don't know if any funded scientific research has been conducted (don't know an oganization the would fund this), but there are loads of empirical data fom hobbyists and professionals alike. Rock, being porous, has the capability to absorb nutrients if kept in a high nutrients environment and due to diffusion, th nutrients will leach in a low nutrient (ie. Our tanks) environment. So, a rock obtained from an area (for example) with high levels of runoff could collect nutrients from fertilizer or pollutants and if concentrations remain high enough for a period of time, yes, it can leach inorganic nutrients.

With live rock, in particular, the nutrients are typically a result of organisms living on the rock. When we get live rock, typically it is exposed to air for a period of time. While many organisms can tolerate this, a great many cannot (sponges are particularly succeptible to this due to air getting trapped in the spicules and preventing future water flow through). Decaying organics release nitrogen and phosphorous along with a number of other compounds.

So, I don't have a study to cite, but experience and a number of biology and Chem classes can back it up.

 

[brandon429]

how about this mode as well:


any person here can take out their live rocks and set them in a white bucket of holding water


check back in two days, the bottom is littered with detritus and N and P is still in the detritus, which is testable as well compared to control water (simply concentrate the detritus, let it sit 48 hours in small batch sample water, then test using extremely good quality gear)
live rock makes whole waste due to the animals in and on, that's a constant source of N and P




Some of these posts are referring to phosphate coming out of the actual crystalline structure of the live rock as its bound

When there's dried up waste on the rock that is rehydrated, not long after nitrate will result

there is no chemical storage mechanism for nitrate in the rock lattice like there is for phosphate...Randy has said bascially that summation on other nitrate threads I recall them clearly.

Phosphate has a storage mechanism in the crystalline structure

how that po4 gets out and back into bioavailability is what id like to see

 

[DanConnor]

I assume the original post refers to dead or mined rock. Anyone can observe how easily it grows algae in relatively clean water, while cured live rock and inert fixtures remain algae-free in similar conditions.

 

[Reef man 89]

This is what I was thinking when it comes to leaching po4 not so much no3. So I started my tank with dry pukani Rock. Cured the rock in a bin for 2 months before I started my tank. After my cure there was zero no3 and zero po4. But from what I have read here on r2r from other members. That pukani is a very nice looking rock and huge surface space for bacteria to live. That after a year or two the rock itself will start to leach po4 into the water. That is what I was wondering about. Is this actually possible to have your rock leach po4 or is the po4 coming from another source?

 

[DanConnor]

That you might need a study for. Once the rock is covered with coralline etc I no longer worry about it. To me the issue is algae extracting nutrients directly from the rock, rather than nutrients in the water.

 

[brandon429]

the collective effect of millions of cells digesting their intended foodstuff on top of the rock as epibenthic communities is digestive acids in proximity to caco3 matrix, limestone, and they degrade it away slowly in time leaching the po4.

Some species of bacteria dissolve rock for nutrient access

google scholar I bet a few search terms like:

microbiological digestion of calcium carbonate

mechanisms of lithotrophic bacteria

limestone as a phosphate reservoir

exchange mechanisms for organic and inorganic phosphate with calcium carbonate substrates

something along those lines w get it

I have an interesting opinion on phosphate
don't care what presence it has in my tank, never tested for it, my tank is algae free independent of nutrients. what a load off from stress that mode has shown to be. I've only used purple Coral in live rock for my reef so I've never had to do a curing process

 

[sundog101]

As stated above rocks or stuff on the rocks could contain N and P. Obviously dying organisms or decaying material is going to show a rise in nutrients.

I think the real question is can the rock itself absorb N and P and then release it at a later time.

 

[Bperau]

I put a rock from my biocube that had an algae issue in my 125 reef tank that has 0 algae and after scrubbing the rock clean it was the only rock that had hair alage grow on it. Never transferred to any rocks sitting right next to it, just one rock lol

 

[sullyman]

Rock absolutely leaches junk/foul fuel back into the tank once the rock has stopped working, full of detrius.You need to blow rocks off before water changes.

 

[jeffmr4]

I had this problem in my tank with some bad live rock. I had algae problems from day 1. I reduced my nitrates and phosphates to nil but still had algae growth. I removed the rock, vacuumed the sand (which I had been doing), and replaced the rock with carib sea life rock. So far no problems. I think phosphate in the rock can be bound with other things like calcium so it doesn't go away quickly.

 

[Mark Taber]

Many thanks to all the responses. I too think it does but logic would point away from this. If live rock acts like a sponge and absorbs N04 and P04, then it must get to a saturation point and then cannot take anymore and begin to leak it back into the aquarium. At this point, we are continually feeding our aquarium and the rock can no longer deal with this plus it begins to leak. Therefore Nitrates should skyrocket which they don't, all most people say is they begin to see detections of Nitrate. Also, every rock, sandbed in the sea would now be exhausted and the ocean full of Nitrates.
If live rock eventually leaks P04 and N04, why are we all using it?

 

[brandon429]

but mine doesn't have that problem, so I use it to look reefy in the tank. my live rock sits there for 16 yrs and does nothing bad, but it gets purpler and I like that. I keep the whole system free of detritus, and I don't have to test for any params because of that. lr is my fav, its no work for me. It doesn't even grow algae any longer since I killed it all in the beginning. its perfectly behaved pet rock

 

[hart24601]

From what I understand the phosphate will bind the calcium carbonate - I think calcium carbonate is used in human medicine as a phosphate binder for those with chronic kidney failure which should be plenty of scientific evidence of binding phosphate.

I do not think nitrate bonds LR and therefore any nitrate released would be from dying organisms.

It's my understanding that phosphate release is only of concern if the previous system was maintained at high phosphate concentrations - keep phosphate low and only a small amount will attach, but if there was a system with phosphate at 2ppm for a year and you take the rock and put into a 0.01 ppm system that phosphate will be liberated as it will try and find equilibrium. Now how fast that happens I have no idea.

 

[Mark Taber]

Very interesting, I am still not convinced rock acts as a sponge and gets exhausted and the realises Nitrate and Phosphates but it would be good to see a study on what is actually going on.

 

[hart24601]

If calcium carbonate (live rock) is used medically to bind phosphate why wouldn't live rock bind if phosphates were at high concentration.

Again I have not seen evidence nitrates are bound unless by dead organic creatures.


Take some live rock nothing fancy. Can be from running system. Put in seawater after scrubbing (or use phosphare free dry rock) and test phophate for base after a few weeks.


Keep it at 5ppm phosphate seawater for a month, adjusting to keep level at 5ppm for that time.

Take it out, wash it well.

Put in 0ppm phosphare seawater and test for a month. If phosphate rise put in new o ppm water and record all of it.