Inverts struggling/dying after phosphate dosing?

[penfold2]

My tank is a little over 5 months old and I've never been able to measure detectable phosphates, so I recently started dosing a solution of reagent grade sodium phosphate monobasic (NaH2PO4). For the last 5 days I've been dosing enough to measure 0.1ppm on my Seachem test kit, which is gone again by the next day. But starting yesterday I noticed that my mini brittle stars are dying, several snails are on their backs or extended from their shells, and urchins are sitting on the tank bottom. My corals and hermit crab seem unaffected. I've stopped dosing, but is there any way this product could cause this? I've never had problems with inverts before, and the phosphate dosing is the only thing I can think of that has changed recently.

 

[bluemon]

What are you using to test phosphates?

How are you dosing it?

What are your nitrates at?

 

[Randy Holmes-Farley Verified Community Expert]

Seems likely to be a coincidence as long as that is the exact product.

 

[penfold2]

What are you using to test phosphates?

How are you dosing it?

What are your nitrates at?

I use a Seachem test kit. It's not as precise as a colorimeter, but it gets me in the ballpark, and it comes with a 1ppm reference solution which yields an appropriate measurement.

I'm mixing 1 gram of powder into 100mL of RODI and dosing with a syringe.

I don't measure nitrates. I've read some info that it may not be as important to corals as phosphate.

Seems likely to be a coincidence as long as that is the exact product.

Thanks. It is the exact same product. I couldn't imagine how it could have this effect at such a low concentration, but it was so coincidental with the invert problems. I'll continue to look for other causes.

 

[bluemon]

I use a Seachem test kit. It's not as precise as a colorimeter, but it gets me in the ballpark, and it comes with a 1ppm reference solution which yields an appropriate measurement.

I'm mixing 1 gram of powder into 100mL of RODI and dosing with a syringe.

I don't measure nitrates. I've read some info that it may not be as important to corals as phosphate.


Thanks. It is the exact same product. I couldn't imagine how it could have this effect at such a low concentration, but it was so coincidental with the invert problems. I'll continue to look for other causes.

I would definitely still measure Nitrate. if you had a low phosphate problem, it could be that it was a bottle neck for nitrate consumption by algae, and could have caused high nitrates. And high enough nitrates can be dangerous to inverts.