Phosphates, and what to do, are driving me crazy!

[BriDroid]

I'm fighting low/0 phosphates in my nano. I can't keep them above 0ppm. It's about 3 months old, so I know the rocks and sand are binding them, but I would think that with me dosing them I would be able to see them.

I was dosing 0.2ppm phosphates via a trisodium phosphate solution once a day. If it go and measure 30 minutes to 1 hour later, I'm reading 0ppm on my Hanna ULR checker.

Today, as an experiment, I dosed my normal 0.2ppm PO4 and tested 1 hour later. I got 0.006ppm PO4. I then dosed 0.6ppm PO4. 3 hours later I tested and I'm at 0ppm PO4.

My questions are:
1. Is the rock and sand binding them that fast?
2. Am I safe to keep adding PO4 until I can get a reading on the Hanna ULR checker?
3. If not, how much should I add per day?

 

[KrisReef]

What else in the tank can be consuming P?

If all you have is rocks, dosing a few times a day until it starts reading and rising would be the trick to filling the holes in the rocks. I would go slowly because once they are full the level should climb quickly vs what you are experiencing now.

 

[BriDroid]

What else in the tank can be consuming P?

If all you have is rocks, dosing a few times a day until it starts reading and rising would be the trick to filling the holes in the rocks. I would go slowly because once they are full the level should climb quickly vs what you are experiencing now.

I've got a CUC, a single Springeri damsel and zoas, LPS and SPS in there. The corals and inverts are all doing good and growing. I'm sure they are using some of the PO4 as well. I just feel like it should level out at some point! It was so much easier in the old days when we were shooting for 0 phosphates :D

 

[Miami Reef]

Are you sure you made the phosphate solution correctly? Maybe it’s weaker than you think.

In any case, upping the dose is the answer.

 

[BriDroid]

Are you sure you made the phosphate solution correctly? Maybe it’s weaker than you think.

In any case, upping the dose is the answer.

I sure hope so. I used the James' Planted Tank online calculator... It was acting the same way with NeoPhos before I made the switch, so I "think" it's good?

 

[Miami Reef]

I sure hope so. I used the James' Planted Tank online calculator... It was acting the same way with NeoPhos before I made the switch, so I "think" it's good?

Very interesting. I haven’t heard of rocks binding this aggressively before.

What type of rock did you use? I agree this seems a bit unusual.

 

[BriDroid]

Very interesting. I haven’t heard of rocks binding this aggressively before.

What type of rock did you use? I agree this seems a bit unusual.

It was dry and cleaned rock out of someone's old tank. Some look like real "live rock", very porous and the rest looks like Marco dry rock. I've been setup since 8/8/24. That is the date that I first added the rocks, sand, saltwater and bottled bacteria. I figured it would have found an equilibrium by now!

I also struggle to keep my nitrates up. Dosing Randy's ammonium bicarbonate daily too. NO3 runs anywhere from 0.5-6ppm when I test. At least it doesn't bottom out like the PO4 does.

 

[BriDroid]

The formula that I used for my solution is:
1.1g trisodium phosphate into 250ml of RO/DI water.
My tank volume is 8 gallons of water.
1ml of this should give me 0.1ppm of PO4 in my tank.

 

[Randy Holmes-Farley Verified Community Expert]

I’d just dose more. :)

 

[bossman818]

Keep Dosing. I was at 0 ppm for weeks. Dose daily and slowly increase amount. Finally got a steady reading after a few weeks.

 

[BriDroid]

I’d just dose more. :)

That is what I was thinking, but how much? Can I dose 1ppm in a day or is that too much? My gut feeling is to go slow, and that is what I have been doing so far adding 0.1-0.2ppm a day. Today I tried 0.6ppm and it was gone in a few hours.

 

[Randy Holmes-Farley Verified Community Expert]

That is what I was thinking, but how much? Can I dose 1ppm in a day or is that too much? My gut feeling is to go slow, and that is what I have been doing so far adding 0.1-0.2ppm a day. Today I tried 0.6ppm and it was gone in a few hours.

I don’t think there’s any substantial issue if you are dosing 0.2 ppm, even if it goes to undetectable 24 h later. Corals have time to get some (I might measure 10 min after dosing to be sure there’s not some unknown issue such as test error, wrong product or dose, etc).

But it’s also not going to be a problem to dose 0.5 ppm, as long as you test very frequently.

 

[BriDroid]

I don’t think there’s any substantial issue if you are dosing 0.2 ppm, even if it goes to undetectable 24 h later. Corals have time to get some (I might measure 10 min after dosing to be sure there’s not some unknown issue such as test error, wrong product or dose, etc).

But it’s also not going to be a problem to dose 0.5 ppm, as long as you test very frequently.

That is what I was wanting to hear! Thank you Randy!

 

[KrisReef]

It was dry and cleaned rock out of someone's old tank.

P sponge right there!

Were they cleaned with vinegar or muriatic acid. Opens up the binding spots.

 

[BriDroid]

P sponge right there!

Were they cleaned with vinegar or muriatic acid. Opens up the binding spots.

I'm not sure. I was looking for cheap rock on Marketplace :D They were clean with just a few spots of old Coraline hear and there, so I assume an acid of some kind. This is all starting to make sense now!

 

[KrisReef]

I'm not sure. I was looking for cheap rock on Marketplace :D They were clean with just a few spots of old Coraline hear and there, so I assume an acid of some kind. This is all starting to make sense now!

The P lives in equilibrium with the binding spots in our tanks. As one opens up another P moves in to fill it. ONce they are filled then the levels can rise. Removals by corals lower the concentration in the water so the key is balance.