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live rock leaching phosphate?


linbeg

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Is there anyway to cure or safely remove the live rock of its leaching phosphates without cooking or harming the live rock in any way? If i just wait it out, will all the phosphates from the live rock be removed? Or is there no other way?

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danthenewreefman
Is there anyway to cure or safely remove the live rock of its leaching phosphates without cooking or harming the live rock in any way? If i just wait it out, will all the phosphates from the live rock be removed? Or is there no other way?

 

GFO is the way.

 

keep running media until it leaches no mo

 

no other way I can think of that doesn't harm the life on rock

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Hmm.. The more actual research I do on rock releasing phosphates into the water the more I am swayed to believe that it's BS. The exception is if your pH is low and the rock starts dissolving slowly.

 

Just like activated carbon and GFO, once they "absorb" something, it cannot leach back into the water over time.

 

I would try to re-think the source of your phosphates.

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FishStrings

I think when you get your phosphates in your water real low, the rocks will start leeching the phosphates out. Your phosphate media should remove it at this point and continue to lower it. This should cause hair algae which will fall off big time and cause a mess as in my case. I am having to clean my filter intake strainer once a day from dead algae. Manually removing some of the hair is as good as removing the phosphates themselves.

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I think when you get your phosphates in your water real low, the rocks will start leeching the phosphates out. Your phosphate media should remove it at this point and continue to lower it. This should cause hair algae which will fall off big time and cause a mess as in my case. I am having to clean my filter intake strainer once a day from dead algae. Manually removing some of the hair is as good as removing the phosphates themselves.

 

 

i dont think it works like that, at least not to any significant degree.

 

from a chemistry standpoint phosphates are bound up to another ion (they dont exist in your rock as phosphate, but as say calcium phosphate, magnesium phosphate and sodium phosphate) in order to have phosphates in your water come from these sources you would need to exceed the breaking energy of these bonds. bacteria do this much more efficiently when they break up food, fish poo etc. are your rocks releasing some phosphate ions? sure, but they might account for .001% of your total phosphate concentration.

 

plus, with your logic, your phosphate concentration would never go down. your rock would simply release more as the media removed it ;)

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i know this might sound dumb and sorry to butt in... but when GHA dies "and rots on the rock" does it release Phosphates back into the water ? ....and could that feed new GHA?

Thanks

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i know this might sound dumb and sorry to butt in... but when GHA dies "and rots on the rock" does it release Phosphates back into the water ? ....and could that feed new GHA?

Thanks

 

Yes, when running GFO you need to vacume dead/dieing algae out. Plants only need phosphate to start to grow after that they dont really need it anymore what keeps it growing bigger and bigger is the nitrates.

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FishStrings

When my caulerpa died from the ROWA phos, you can bet hair algae was the first thing there to take its place. Then it started dieing and clogging media, causing buildup. Also: I upped my cleaner crew big time and my urchin and halloween hermit ate a lot of the hair algae.

 

+1

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I think when you get your phosphates in your water real low, the rocks will start leeching the phosphates out. Your phosphate media should remove it at this point and continue to lower it. This should cause hair algae which will fall off big time and cause a mess as in my case. I am having to clean my filter intake strainer once a day from dead algae. Manually removing some of the hair is as good as removing the phosphates themselves.

Bingo. Phosphates will latch on to the rock and sediment until the rate of adsorption equals the rate of release, then it will be in equilibrium, with some phosphates leaving the rock but phosphate in the water binding to the now empty sites. If you put a rock that was in a high phosphate tank into a tank with low phosphates then it will release phosphates until it is in equilibrium with the new system. GFO is the same way, actually, but it has such a high surface area that it takes a very long time to reach the equilibrium point, and it also gets replaced regularly, so there is a net export of phosphates.

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Bingo. Phosphates will latch on to the rock and sediment until the rate of adsorption equals the rate of release, then it will be in equilibrium, with some phosphates leaving the rock but phosphate in the water binding to the now empty sites. If you put a rock that was in a high phosphate tank into a tank with low phosphates then it will release phosphates until it is in equilibrium with the new system. GFO is the same way, actually, but it has such a high surface area that it takes a very long time to reach the equilibrium point, and it also gets replaced regularly, so there is a net export of phosphates.

 

Not trying to start an argument here.....but.....really? It takes some crazy pH conditions for stuff to leach out like you describe. Ever wonder why your rock and sand are not disintegrating into mush in an attempt to balance out the calcium levels? Or why your glass is not dissolving in an attempt to push silicates from the glass into the water? Your tank will crash long before your rock "absorbs" and then "releases" phosphates.

 

Edit: I will fully admit that crap might clog the pores and then "leach" stuff back out. But not actual bound phosphates that have incorporated themselves into the actual chemical structure of the rock. Crap floating out of a rock is a different story than a rinsed/cleaned rock that is "leaching" simply because it went from a high phos to low phos environment.

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http://www.advancedaquarist.com/2002/9/chemistry

 

Likewise, phosphate can precipitate onto the surface of calcium carbonate, such as onto live rock and sand. The absorption of phosphate from seawater onto aragonite is pH dependent, with the maximum binding taking place around pH 8.4 and with less binding at lower and higher pH values. If the calcium carbonate crystal is static (not growing), then this process is reversible, and the aragonite can act as a reservoir for phosphate. This reservoir can make it difficult to completely remove excess phosphate from a tank that has experienced very high phosphate levels, and may permit algae to continue to thrive despite cutting off all external phosphate sources. In such cases, removal of the substrate may even be required.
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Yep. Exactly what I said. From the summary of that article....

 

"Simply keeping the pH high in a reef tank (8.4) may help keep phosphate that binds to rock and sand from reentering the water column. Allowing the pH to drop into the 7’s, especially if it drops low enough to dissolve some of the aragonite, may serve to deliver phosphate to the water column. In such systems (typically those with carbon dioxide reactors), raising the pH may help control soluble phosphate."

 

Unless you have some crazy pH conditions, you are fine :) .

I was not saying that phos cannot bind to rock. I was saying it is not going to leach back out unless there is some crazy pH action happening. Going from a high phos tank to a low phos tank does not equal anything related to pH. Hence that statement about leaching is misleading.

 

The exception is if your pH is low and the rock starts dissolving slowly.

 

And a well deserved shout out to ajmckay for saying what I said....but earlier ;). Hahahaha.

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  • 1 year later...

Going to revive this topic and see if any new research has come up to refute or support this. I've had a brute full of about 100-150lbs of so called florida rock sitting for about 8 months while my 180g gets set up. I had a water sample tested and it came out with 1.5ppm of phosphates. I do plan on running a gfo reactor on the system so should I not even worry? I didn't spend 8k on a tank to look at algae covered rock.

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Went back through the advanced aquarist article. So it makes sense that the effluent from a calcium reactor, which is essentially dissolving aragonite, would contain phosphates. With that said, and only having 1.5ppm of phosphates after 8 months, I'm going to use the rock.

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