Finding the Source of Rising Phosphates

[toddb93]

Was curious if anybody has any insight as to what can be a cause of rising phosphates in a tank with no fish. Here’s the background:

Currently in a fallow period due to fish disease. In this time I was looking forward to managing nutrient levels. I have come to find out that my phosphates continue to increase with only one cleaner shrimp and serpent star and snails in the tank. At the moment I am running rowaphos to manage because if I do not phosphates rise. I am only feeding this tank 1-2 times per week with a very small amount of frozen mysis just so the starfish, shrimp and snails have something throughout the weeks.

The only thing that is being dosed into the tank is All for Reef 5ml daily. And I did test my RODI water with and without salt mix, and readings came out to .01, so I do not think it is from this.

Tank was started with rock that was once live and before going into my tank it was sitting in a 50 gallon garbage can in saltwater circulating with no light and covered. Is it possible this is die off from the rock? But the tank has been running for 2.5 years so I don’t think it can be from the rock. But who knows

Any thoughts would help, just looking for other things to investigate.

Thanks in advance!

 

[KrisReef]

Phosphate will adhere to rocks and sand. When you remove it from the water column with Rowaphos then it can be released from the substrates and provide a continuous source of P until the substrates have released their attached load and then the level should finally start to drop and not bounce back.

 

[toddb93]

Phosphate will adhere to rocks and sand. When you remove it from the water column with Rowaphos then it can be released from the substrates and provide a continuous source of P until the substrates have released their attached load and then the level should finally start to drop and not bounce back.

Interesting, but you think this is possible even with the rock and sand being in the tank for 2.5 years now?

 

[KrisReef]

Interesting, but you think this is possible even with the rock and sand being in the tank for 2.5 years now?

Especially since it’s been able to absorb P for 2.5 years. Old tank rock is generally in equilibrium with tank levels which tend to rise over time.

Otherwise you could have a testing error, but what you have described fits old, P saturated rocks.

 

[toddb93]

Especially since it’s been able to absorb P for 2.5 years. Old tank rock is generally in equilibrium with tank levels which tend to rise over time.

Otherwise you could have a testing error, but what you have described fits old, P saturated rocks.

Especially since it’s been able to absorb P for 2.5 years. Old tank rock is generally in equilibrium with tank levels which tend to rise over time.

Otherwise you could have a testing error, but what you have described fits old, P saturated rocks.

Ok good to know, I appreciate you answering this thread. Any way as to know how long it would generally take for the P to drop out?

 

[Randy Holmes-Farley Verified Community Expert]

Interesting, but you think this is possible even with the rock and sand being in the tank for 2.5 years now?

It has nothing to do with time. It has everything to do with whether the rock and sand has been exposed to high phosphate. After that happens, the phosphate is bound. It then comes back off any time you try to lower phosphate.

 

[toddb93]

I

It has nothing to do with time. It has everything to do with whether the rock and sand has been exposed to high phosphate. After that happens, the phosphate is bound. It then comes back off any time you try to lower phosphate.

thanks for the reply Randy. Always appreciate the input. Is there any particular way that you recommend managing this?

 

[Randy Holmes-Farley Verified Community Expert]

I

thanks for the reply Randy. Always appreciate the input. Is there any particular way that you recommend managing this?

If the goal is lowering it, there are many ways, but I strongly stress going slow. Plenty of people without problems get them by “fixing” high phosphate too fast. GFO, lanthanum, aluminum oxide, and growing macroalgae all work and each has pros and cons.

 

[toddb93]

If the goal is lowering it, there are many ways, but I strongly stress going slow. Plenty of people without problems get them by “fixing” high phosphate too fast. GFO, lanthanum, aluminum oxide, and growing macroalgae all work and each has pros and cons.

Ok sounds good, yeah I’ve just been running rowaphos and lowering it fairly slowly, I will just keep at it. Do you happen to also know if there is any contraindications to using rowa as well as carbon dosing as long as I keep a slow paced reduction?

 

[Randy Holmes-Farley Verified Community Expert]

Ok sounds good, yeah I’ve just been running rowaphos and lowering it fairly slowly, I will just keep at it. Do you happen to also know if there is any contraindications to using rowa as well as carbon dosing as long as I keep a slow paced reduction?

No, as long as there is adequate N and P, and trace elements do not become limiting to bacteria/carbon dosing.

 

[toddb93]

No, as long as there is adequate N and P, and trace elements do not become limiting to bacteria/carbon dosing.

Perfect, thank you. Again, always appreciate the input.

 

[Finn450]

I recently had a major hair algae problem...first one in my "career". I tried for months to identify the source with no results. I realized the rocks, pukani style, that I recently aquascaped with could be the problem. Removed the rocks, phosphate came down...and have stayed down.

 

[charleydavis]

It has nothing to do with time. It has everything to do with whether the rock and sand has been exposed to high phosphate. After that happens, the phosphate is bound. It then comes back off any time you try to lower phosphate.

An easy way to determine if the old rockis releasing phosphate into the water would be to remove the rock and re-test for phosphate. If phospahte gets low and stays low you can be reasonably certain that the source was the rock.

 

[StealthLabs]

I recently had a major hair algae problem...first one in my "career". I tried for months to identify the source with no results. I realized the rocks, pukani style, that I recently aquascaped with could be the problem. Removed the rocks, phosphate came down...and have stayed down.

As a result did you end up removing these rocks? If so, are you open to selling them?

 

[Finn450]

As a result did you end up removing these rocks? If so, are you open to selling them?

yes, removed rocks...was the source. Sold them to someone that was going to take the effort to rid them of phosphate...hated to see them go.