Let's talk phosphate levels

[Randy Holmes-Farley Verified Community Expert]

Well, the highly variable experiences and opinions expressed here so far are basically why the thread was started. There's no clear consensus.

 

[Rolliad]

Use it as a limiting dose so you do not over do it, and repeat it as needed. One cannot calculate how much is bound in a reef tank.

Sounds good! I'll just keep going as I am! Thanks Randy!

 

[Randy Holmes-Farley Verified Community Expert]

Maybe we can though? If rock leaches at a rate consistent to the amount reduced for instance, that could be accounted for. I just don't happen to know.

I do know the chemical details (binding studies have been published by chemical oceanographers), but what no reefer knows (without doing this exact experiment) is how many square centimeters of available calcium carbonate surface area is in the tank, and how much is partly or completely blocked by other things that may compete with phosphate for binding sites (magnesium, silicate, organics, bacteria, etc.).

 

[bubbgee]

Well, the highly variable experiences and opinions expressed here so far are basically why the thread was started. There's no clear consensus.

This is better than saying.. there is no such thing as phosphates.. like..

 

[geologeek]

Maybe we can though? If rock leaches at a rate consistent to the amount reduced for instance, that could be accounted for. I just don't happen to know.

Unfortunately reef chemistry is a little too complex and the amount of phosphate released is not going to be linear, so you are not going to be able to calculate exactly how much is going to be released if you remove X amount via whatever method you use.

 

[areefer01]

So what is the latest consensus with the poll or what is the next step?

So far I see:

• Votes: 21 - My phosphate was above 1 ppm. I lowered it below 0.15 ppm, and corals had lasting improvement.​

• Votes: 14 - My phosphate was above 1 ppm. I lowered it below 0.15 ppm, and corals had no lasting improvement.​

• Votes: 18 - My phosphate was above 0.5 ppm. I lowered it below 0.15 ppm, and corals had lasting improvement.​

• Votes: 22 - My phosphate was above 0.5 ppm. I lowered it below 0.15 ppm, and corals had no lasting improvement.​

• Votes: 70 - I have never had an experience in lowering phosphate that much.​

• Votes: 22 - I don't know
  
  

  

 

[Dom]

Well, the highly variable experiences and opinions expressed here so far are basically why the thread was started. There's no clear consensus.

This is a great thread. I've learned a lot...

 

[av8]

In my old tank, I noticed polyp extension and coral health looked the best between .1-.2. Anything above .2 and things started to look a little less healthy and they’d improve again once I added GFO.

Currently I’m having trouble keeping phosphate above .03. Dosing phosphates daily seems to keep them happy.

What are you using (dosing) with? to raise phosphates?

 

[Randy Holmes-Farley Verified Community Expert]

What are you using (dosing) with? to raise phosphates?

Best bet, IMO, is food grade sodium phosphate.

 

[sixty_reefer]

I do know the chemical details (binding studies have been published by chemical oceanographers), but what no reefer knows (without doing this exact experiment) is how many square centimeters of available calcium carbonate surface area is in the tank, and how much is partly or completely blocked by other things that may compete with phosphate for binding sites (magnesium, silicate, organics, bacteria, etc.).

Could bacteria respiration be one of the main culprits in phosphate desorption?

Denitrifying bacteria tends to be deep into the rock in anoxic areas and produce co2 as a byproduct, potentially lowering ph inside the rock that could dissolve aragonite.

Could be an interesting test for someone as this would have to also increase some calcium as a side effect.

 

[ccole]

What are you using (dosing) with? to raise phosphates?

I’m using Neophos! I use 50-100 mL a day depending on my reading from the night before. My system is about 230 gallons and seems to process about .05 phosphate a day.

 

[Randy Holmes-Farley Verified Community Expert]

Could bacteria respiration be one of the main culprits in phosphate desorption?

Denitrifying bacteria tends to be deep into the rock in anoxic areas and produce co2 as a byproduct, potentially lowering ph inside the rock that could dissolve aragonite.

Could be an interesting test for someone as this would have to also increase some calcium as a side effect.

The pH is typically lower down in sand beds, but I do not think denitrification is the cause. Denitrification consumes acid to make CO2, so it’s not the main cause of low pH.

organic + 124 NO3– + 124 H+ → 122 CO2 + 70 N2 + 208 H2O

Aerobic degradation of organics, however, does lower pH.

In any case, unless the pH values are changing, pH is not causing absorption or desorption.

 

[Brian916]

I couldn't make a response because my situation isn't on the list. I let my Phos creep up to ~1.2 (neglect) and I saw more GHA and slow coraline / coral growth. I slowly dropped my Phos to ~0.5 and coraline growth notably approved and some coral growth appears to be more robust. I might bring it down a bit further, but I am not too fussed about it.

I feel like coraline is a better indication than short term coral response to Phos and Alk changes. Many corals are so fussy that they respond poorly to any change even if it is a "good" change....

 

[Rolliad]

I think this thread is basically dead, but for anyone that was following along. I FINALLY got a reading on my phosphate this morning on my Hannah tester of 1.75ppm. Going to keep bringing it down as I have been until it's at .8ppm and then come in for a "soft landing" at somewhere around .2ppm or so and see where we're at at that time.

Also - while everything else in the tank is responding well to the phosphate coming down - the leathers are very angry and have retracted their polyps for the last 2 days.

 

[Randy Holmes-Farley Verified Community Expert]

I think this thread is basically dead, but for anyone that was following along. I FINALLY got a reading on my phosphate this morning on my Hannah tester of 1.75ppm. Going to keep bringing it down as I have been until it's at .8ppm and then come in for a "soft landing" at somewhere around .2ppm or so and see where we're at at that time.

Also - while everything else in the tank is responding well to the phosphate coming down - the leathers are very angry and have retracted their polyps for the last 2 days.

How are you lowering it?

 

[Rolliad]

How are you lowering it?

Two Little Fishes PhosBan - L. 15 ML/day of the diluted solution as per the instructions. It's lanthanum chloride.

I divide the 15ml up into 3 x 5ml doses down the main drain into the filter roller. 1 dose in the morning, 1 mid day, and 1 in the evening.

It causes the filter roller and then the skimmer to go insane for about 35-40 minutes. The skimmer pulls out almost a milky sand like consistency in the skimmate from it. It takes ~3 hrs for the water clarity to return after a dose.

 

[Randy Holmes-Farley Verified Community Expert]

Two Little Fishes PhosBan - L. 15 ML/day of the diluted solution as per the instructions. It's lanthanum chloride.

I divide the 15ml up into 3 x 5ml doses down the main drain into the filter roller. 1 dose in the morning, 1 mid day, and 1 in the evening.

It causes the filter roller and then the skimmer to go insane for about 35-40 minutes. The skimmer pulls out almost a milky sand like consistency in the skimmate from it. It takes ~3 hrs for the water clarity to return after a dose.

Reason I ask is that leathers historically reacted poorly to Seachem Phosguard. I believe they did not care for aluminum.

 

[Rolliad]

Reason I ask is that leathers historically reacted poorly to Seachem Phosguard. I believe they did not care for aluminum.

When I was researching products, people seemed to not like Phosguard and PhosBan L got really good press/reviews and given my own personal history using TLF products, I went with them.

Plus, considering I was also working previously this month to remove aluminum from the water, I didn't feel like it would be smart to add it back with another product. Seems disrespectful of my own time, even though I'm not a chemist. LOL

 

[Gregg @ ADP]

At this point, I feel like I’ve seen every conceivable reaction to every conceivable PO4 level by every conceivable coral.

I’ve seen >1.0 tanks do great. I’ve seen >1.0 tanks suffer. I’ve seen tanks at 0.01 doing great, and others doing terribly. At this point, to the extent that I have a PO4 target, I like things between 0.3-0.5.

One thing I will say…if I feel the need to adjust PO4 levels, I do it very, very slowly.

 

[Garf]

Ive noticed no observable difference of 0.2 to 03 pO4. Nana, zip, diddly squat. Stuff grows ok at 0.3.