Rocks leaching phosphate

[rayn]

Working towards setting my tank back up. I have always bought dry rock from my lfs and seeded from maybe a piece or two of live. Other then that I cycle by throwing a shrimp in to start it. Have on every tank I set up.

Thinking ahead a bit on this one, almost every tank I battle with HA and highish phosphate. I can usually control them through GFO or phosguard. I wonder if there is a way to actually pull the phosphate out during the cycle or right after try cycle from the rock...or is it something that has to be done as the tank matures?

 

[saltyfilmfolks]

I'd love to see something that actually says that rocks are the cause of high phosphate in the tank. As I understand it its food.
Honestly curious.

 

[Smite]

I'm not sure as far as during the cycle but I took some LR that seemed to be really leaching phosphates in my last system and gave it a muriatic bath. From what I understand that pulls the phosphates out. I haven't got the system wet yet, but i'll be checking for phosphates for a bit before I transfer my livestock.

LR is porous, so I believe it can absorb and hold phosphates, then slowly leach them back out over time.

 

[rayn]

This rock has been previously bleached and dried. Not quite the muratic acid bath, but cleaned I was hoping for the most part. Doesn't the muratic acid actually eat away at the rock?

 

[Randy Holmes-Farley Verified Community Expert]

This rock has been previously bleached and dried. Not quite the muratic acid bath, but cleaned I was hoping for the most part. Doesn't the muratic acid actually eat away at the rock?

Yes, that is how it removes phosphate that has become part of the surface of the calcium carbonate crystals. Bleaching will remove organic matter, and that is a desirable thing, but it won't remove much inorganic phosphate.

 

[Randy Holmes-Farley Verified Community Expert]

I'd love to see something that actually says that rocks are the cause of high phosphate in the tank. As I understand it its food.
Honestly curious.

"the cause" will, of course, depend on many factors, and foods are typically a much bigger source than any other source. But calcium carbonate rock and sand certainly is known to bind phosphate from seawater, and the higher the concentration of phosphate in the water, the more binds to the rock. So rock coming out of an aquarium that had elevated phosphate will have a significant amount bound to it. Also, certain types of mined dead rock that have been exposed to surface runoff for long periods (perhaps even thousands of years) may have substantial phosphate in it.

 

[Randy Holmes-Farley Verified Community Expert]

Working towards setting my tank back up. I have always bought dry rock from my lfs and seeded from maybe a piece or two of live. Other then that I cycle by throwing a shrimp in to start it. Have on every tank I set up.

Thinking ahead a bit on this one, almost every tank I battle with HA and highish phosphate. I can usually control them through GFO or phosguard. I wonder if there is a way to actually pull the phosphate out during the cycle or right after try cycle from the rock...or is it something that has to be done as the tank matures?

The phosphate on the rock is in equilibrium with phosphate in the water. So having the rock in water with a low to very low phosphate concentration will slowly remove it from the rock. You can do that before setup, or you can keep it low during the cycle (or both). There are a variety of ways to accomplish this, including GFO, lanthanum (especially in pre-treatments) and acid washing.

 

[rayn]

With that info I need to check my mixed water for phosphate. Possibly if it is low enough to 0 I will just add and scape my tank. If I register phosphate, then maybe it will be better to do the muratic bath.

I am supposing this needs to be done outside though, correct?

 

[Randy Holmes-Farley Verified Community Expert]

With that info I need to check my mixed water for phosphate. Possibly if it is low enough to 0 I will just add and scape my tank.

The water going in is not the concern, and will be very low. The problem is that as soon as the rock sits in it, phosphate can come off and the level in the water will rise.

So what is needed is an active means to keep it low when the water is in contact with the rock.

 

[saltyfilmfolks]

The water going in is not the concern, and will be very low. The problem is that as soon as the rock sits in it, phosphate can come off and the level in the water will rise.

So what is needed is an active means to keep it low when the water is in contact with the rock.

Good Morning Randy,
Thank you for joining the conversation.
My question would be this:
By prophylactic use of GFO in a new tank would this adversely affect the development of the beneficial bacteria?

Understandably if old live rock and sand is used there is a higher concentration of PO being added to tank. But if dry rock or dry sand and canned bacteria is added(most sterile new cycleing) is used I dont see the need for it.
As with silica it would depend on the concentration in the particular rock/sand being used.

PO reduction as I understand it is the reverse of dosing. By observing the PO output of the tank you remove it at the given rate to achieve recommended levels for the livestock in the tank.
In a new tank I dont see how that can be done as leeching shouldn't generally occur that quickly and measurement would be impossible given the slower rate of addition and time. If it took a thousand years to get it in, a reactor is not going to do much to get it out in any noticeable way.

In cycling a tank with cured or seeded(trusted tank water and or live rock) I would assume it would strip nutrients needed for Micro algaes for sure.
It seems there is a particular fear of Po in aquaria and it should also be viewed as benificial, although not in high concentrations.
In reference to the OP original question Measurement should likely be done over weeks(6-8) and months and a good cleaning of organic matter from the rock is definately the best thing. Although I always suspect sand before rock.

 

[Randy Holmes-Farley Verified Community Expert]

If you are particularly concerned about phosphate on the rock you are using, I'd probably treat the rock before cycling since there's no concern about how low the levels might get.

I do not know how low levels can be for the nitrogen cycle bacteria to get along, but probably pretty low. Folks without any apparent source of phosphate can cycle a tank with ammonia alone. But to be conservative, treatment before cycling would eliminate the issue (assuming we are talking dead rock and not uncured live rock).

Let me describe the binding process a little bit. The phosphate we are talking about is on the surface of the rocks and sand and is in fairly rapid equilibrium with the water. Minutes and hours, not years and decades. None of the phosphate buried deep in the rock will ever come out (unless some of the rock eventually dissolves away) and is no concern in this context. Phosphate deep in pores will take longer, but can come out.

This binding is why a 100% water change does not eliminate phosphate from the water, while it will mostly eliminate nitrate.

FWIW, some dead rock is apparently loaded with phosphate, and folks seem to have significantly better success if they strip out the phosphate prior to using it.

 

[rayn]

Sounds like possibly the best option is to set a tank up, or a holding tank of some sort, and start the cycle. This would allow you to cycle the rock and use some sort of phosphate binder before the rock goes into the display.

If phosphates register high during this process, I suppose one could acid dip them and just start over again too.

 

[saltyfilmfolks]

The phosphate we are talking about is on the surface of the rocks and sand and is in fairly rapid equilibrium with the water. Minutes and hours

So the phosphate on dead rock can be nearly immediately read once introduced to the water? Also the same question for uncured live rock.

I've read so much of your work I have fairly good understanding of the binding process.(thank you). What Im noticing recently(and why I ask) is so many are trying to remove phosphate before there is an apparent source, and having recently set up a tank from dry, I had the typical high phosphate problems.. But I have observed with others using GFO reduction, they are having cycling problems. So Im trying to glean a good test method

 

[saltyfilmfolks]

Working towards setting my tank back up. I have always bought dry rock from my lfs and seeded from maybe a piece or two of live. Other then that I cycle by throwing a shrimp in to start it. Have on every tank I set up.

Thinking ahead a bit on this one, almost every tank I battle with HA and highish phosphate. I can usually control them through GFO or phosguard. I wonder if there is a way to actually pull the phosphate out during the cycle or right after try cycle from the rock...or is it something that has to be done as the tank matures?

Hi Ryan, with my last build being the exception, I have had the best success by cleaning the heck out of the rock and putting it in the tank and cycling it. I do also have a completed(nearly) experiment that I cycled cleaned dead sand and dead live rock in a 5 gallon bucket with a powerhead and water from my DT water change. Took almost exactly 4 weeks and the Params are perfect. Weird right? having a tank with probs and a bucket with none.
By nearly i mean I need to get it into a tank, its been now nearly 8 weeks with still good params.
Btw Im a Fuge guy and only GFO when the Params get to high.
Thanks for the thread. Figuring out how to test for a "bad rock" would be pretty useful.

 

[tankstudy]

Figuring out how to test for a "bad rock" would be pretty useful.

For dry rock, what I do is toss it in a bucket of RO/DI and test it a couple days later. If you are getting phosphate readouts, your rocks are leaching phosphates. I use an Ultra Low Phosphate Hanna meter.

 

[Randy Holmes-Farley Verified Community Expert]

So the phosphate on dead rock can be nearly immediately read once introduced to the water? Also the same question for uncured live rock.

I've read so much of your work I have fairly good understanding of the binding process.(thank you). What Im noticing recently(and why I ask) is so many are trying to remove phosphate before there is an apparent source, and having recently set up a tank from dry, I had the typical high phosphate problems.. But I have observed with others using GFO reduction, they are having cycling problems. So Im trying to glean a good test method

As tankstudy mentions, if you soak dead rock for a day or two in normal seawater and do not detect more than 0.03 ppm phosphate, there should not be a concern.

Uncured live rock is a different different issue because it may have a lot of dead organic tissue on it which can become a source of nutrients if not removed, but won't immediately be released.

 

[saltyfilmfolks]

As tankstudy mentions, if you soak dead rock for a day or two in normal seawater and do not detect more than 0.03 ppm phosphate, there should not be a concern.

Uncured live rock is a different different issue because it may have a lot of dead organic tissue on it which can become a source of nutrients if not removed, but won't immediately be released.

Thank you Randy.

Thank you Rayn, Thank you Tankstudy.
I think someone should sticky this. I have not easily found this concise a write up in several weeks of searching.

 

[rayn]

I haven't ever used all live rock before, though I have seeded from some. I have always used the shrimp cycle method. Over the years I have accumulated rock...all dry. Where it comes from, I have no idea.

I still think after all the posts, I should set something up and figure out if and where phosphate is coming from.

Thanks to all posting, I always learn something!

 

[benapilot]

Years ago when I started my first reef tank, I used a combination of LFS live rock and dead coral rock from the beaches on Hawaii. I went through a year long battle with green hair algae. I'm not sure if that was associated with the Hawaiian rock or whatever else was going on in the aquarium. I never saw any algae on the Hawaiian rock, just the live rock I got from my LFS. Phosphates were always low, but I never tested for it until I saw the hair algae outbreak- from what I've read, the phosphate would have been low because of all the hair algae. It took a while, but I won the battle!

Fast forward to today... I've upgraded from 46 to a 75 gallon tank. I brought home more beautiful bleached dead coral rock from Hawaii and have it in a 5 gallon bucket with some of my existing live rock, heater and power head. It sat in my old tank water (phosphate-free) for a couple weeks. Two days ago I changed the water- today I tested it and my Hannah Checker read .35. That's pretty high. Could that be coming from the Hawaii rock? Is there anything that could be dying off from my existing live rock rubble from being out of the light?

I'll do another water change in that bucket and test again in a few days. I certainly DON'T want that rock in my tank if it's going to be leaching that much phosphate. I have a BRS reactor set up that will eventually house either GFO or biopellets. How much phosphate can those methods absorb?

 

[saltyfilmfolks]

Years ago when I started my first reef tank, I used a combination of LFS live rock and dead coral rock from the beaches on Hawaii. I went through a year long battle with green hair algae. I'm not sure if that was associated with the Hawaiian rock or whatever else was going on in the aquarium. I never saw any algae on the Hawaiian rock, just the live rock I got from my LFS. Phosphates were always low, but I never tested for it until I saw the hair algae outbreak- from what I've read, the phosphate would have been low because of all the hair algae. It took a while, but I won the battle!

Fast forward to today... I've upgraded from 46 to a 75 gallon tank. I brought home more beautiful bleached dead coral rock from Hawaii and have it in a 5 gallon bucket with some of my existing live rock, heater and power head. It sat in my old tank water (phosphate-free) for a couple weeks. Two days ago I changed the water- today I tested it and my Hannah Checker read .35. That's pretty high. Could that be coming from the Hawaii rock? Is there anything that could be dying off from my existing live rock rubble from being out of the light?

I'll do another water change in that bucket and test again in a few days. I certainly DON'T want that rock in my tank if it's going to be leaching that much phosphate. I have a BRS reactor set up that will eventually house either GFO or biopellets. How much phosphate can those methods absorb?

Randy F gave me this test. Use fresh mixed sea water put the rock in test the po. Wait some time(days) test again. Po will slowly leach out tro be read on test kit. To remove the po, use gfo in the curing tank. in reactor or in bag, obviously reactor or higher flow on gfo etc equeals higher removal rate. GFO binds faster than the rock leaches.

not sure on the absorption rates. hair algae will grow in low Po:mad:.