Adding phosphates to water change

Biologic

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Hey all,

So I am pitching an idea that I haven't seen or I cannot seem to find it as a topic. I have a 100L tank, only a couple of damsels, one ocellaris, and one jerk pseduochromis. My alkalinity consumption is 1 dKH, I am carbon dosing on and off, at minimal amounts to keep a healthy bacteria population and keep Nitrates low. I have dinoflagellates blooms at less than 0.01 ppm phosphate.

My phosphates bottom out quickly in this system. I am due for a water change coming up soon. Could I add in SeaChem Flourish (PO4 additive, which has a handy calculator online) and add this to my water change to keep my phosphates at an acceptable level?

Picture attached shows I increased my phosphates by dosing Flourish, which got rid of my dinos. Days later, 0.01 ppm. Tested via Hanna Phosphorus ULR. The spike today shows a manual correction in phosphates when I added 1.0 mL of Flourish, which brought me up from 0.01 ppm to 0.07 ppm PO4.

IMG_6732.jpg
 
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Randy Holmes-Farley

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like I said, I have just a few fish. This is only 100L. They are not like tangs or anything that you can feed and feed. The pseudochromis is difficult to add any new fish as well.

You can add phosphate to new salt water, but it will all come at once.

When feeding more for this purpose, it doesn't necessarily take much and fish do not actually need to consume it.
 
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Biologic

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Yea. Feed more. And how "low" are your nitrates?.. and how did your phosphates drop 0.14 in 3 days. Is it a new tank?
Response above for food. My only option is dump in more coral food. Which could be a good thing.

Nitrates were at 5.3 ppm (Hanna Dilution Method) when my PO4 was at 0.15 ppm. I dosed daily ESV Calcium Nitrate to drive that number. I haven’t tested NO3 since that low 0.01 PO4 reading. I’d assume they are somewhere on my average of 0.2 ppm.

Started this tank in August 2020.
 
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Biologic

Biologic

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You can add phosphate to new salt water, but it will all come at once.

When feeding more for this purpose, it doesn't necessarily take much and fish do not actually need to consume it.

what about a continuous water change? I notice when my phosphates drop, the corals are ticked off. Making the point coming in all at once isn’t good either. I would prefer if I can adjust NO3 to keep it consistent as well.

I feed pellets once daily.
 

Randy Holmes-Farley

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what about a continuous water change? I notice when my phosphates drop, the corals are ticked off. Making the point coming in all at once isn’t good either. I would prefer if I can adjust NO3 to keep it consistent as well.

I feed pellets once daily.

An AWC is a fine method. I used it for many years.

But the phosphate level needs to be pretty high in the 1% you might change daily. Maybe 2-3 ppm. That might be OK, but I'm not seeing a reason that it is better than just dosing.
 
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Biologic

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An AWC is a fine method. I used it for many years.

But the phosphate level needs to be pretty high in the 1% you might change daily. Maybe 2-3 ppm. That might be OK, but I'm not seeing a reason that it is better than just dosing.

I could just figure out consumption like any other parameter like alkalinity, and set it up to autowater change continuously. Usually I have it set up for 1000 mL of fresh made salt mix changed daily + whatever the rate of consumption need to maintain 0.03-0.06 ppm phosphate.

When I was changing my water at 1000 mL daily, 1% daily, would cause Dinoflagellate break outs. Since I got a handle of PO4, keeping that up really solved my dinoflagellate problem. I beat it three times since August. Low PO4 does it to me every time.

Dumping food in could help, but sodium monophosphate would be significantly less expensive. The fish I have can only eat a certain amount. I can’t add much more but maybe a damsel.
 
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Rubberfrog

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I could just figure out consumption like any other parameter like alkalinity, and set it up to autowater change continuously. Usually I have it set up for 1000 mL of fresh made salt mix changed daily + whatever the rate of consumption need to maintain 0.03-0.06 ppm phosphate.

When I was changing my water at 1000 mL daily, 1% daily, would cause Dinoflagellate break outs. Since I got a handle of PO4, keeping that up really solved my dinoflagellate problem. I beat it three times since August. Low PO4 does it to me every time.

Dumping food in could help, but sodium monophosphate would be significantly less expensive. The fish I have can only eat a certain amount. I can’t add much more but maybe a damsel.
I really feel like you're over complicating it for the sake of overcomplicating it. One or two extra flakes is all you need. If the fish eat it, great. Corals love fish poop. If the fish don't eat it, no problem. Corals love broken down fish food.
 

Randy Holmes-Farley

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I could just figure out consumption like any other parameter like alkalinity, and set it up to autowater change continuously. Usually I have it set up for 1000 mL of fresh made salt mix changed daily + whatever the rate of consumption need to maintain 0.03-0.06 ppm phosphate.

When I was changing my water at 1000 mL daily, 1% daily, would cause Dinoflagellate break outs. Since I got a handle of PO4, keeping that up really solved my dinoflagellate problem. I beat it three times since August. Low PO4 does it to me every time.

Dumping food in could help, but sodium monophosphate would be significantly less expensive. The fish I have can only eat a certain amount. I can’t add much more but maybe a damsel.

Yes, that's a fine plan and is probably going to take something like 2-3 ppm phosphate in the new salt water.

The complexity with phosphate is that it takes far more to raise it than a simple calculation, because so much binds to bare rock and sand surfaces. In one experiment, over 50 ppm of phosphate bound before 0.2 ppm of phosphate remained in the water. Thus it may take a while and some trial and error adjustment.
 

jarviz

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Yes, that's a fine plan and is probably going to take something like 2-3 ppm phosphate in the new salt water.

The complexity with phosphate is that it takes far more to raise it than a simple calculation, because so much binds to bare rock and sand surfaces. In one experiment, over 50 ppm of phosphate bound before 0.2 ppm of phosphate remained in the water. Thus it may take a while and some trial and error adjustment.
and binding media keeps pulling it fom the water until there's an equilibrium between the rocks/sand and water right?... so in theory phosphates can eventually be 0 in the tank as long it's being exported faster than it's being introduced?
 

Randy Holmes-Farley

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and binding media keeps pulling it fom the water until there's an equilibrium between the rocks/sand and water right?... so in theory phosphates can eventually be 0 in the tank as long it's being exported faster than it's being introduced?

Right!
 

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