Why do I show elevated phosphates right after a water change?

[optimisticdingo]

So I've noticed that if I test phosphate directly after a water change I read elevated levels. If I check the next day the levels are more normal to what my tank has been reading.

I'm using the Hanna Phosphate checker, the standard one not the ULR.

In my 116 gallon my Phosphate was at .6ppm, after a 30% water change I checked and Phosphate was over 2ppm. I checked the next morning and it was down to .22. I'm not using a refugium or GFO so it seems that the levels elevate right after a water change. Any idea what causes this?

 

[vetteguy53081]

Worst time to test is right after a water change when the tank is agitated from activity. Wait 12 hrs and reattempt test

 

[blasterman]

Have you tested your salt mix?

 

[optimisticdingo]

Have you tested your salt mix?

No. It's Tropic Marin Pro Reef Salt

 

[GoVols]

Worst time to test is right after a water change when the tank is agitated from activity. Wait 12 hrs and reattempt test

+1

 

[LisaAP]

I found the same, Tropic Marin Pro Reef is not phosphate free. I found as much as 0.1ppm on freshly mixed TMPR using the Hanna ULR tester. However that wouldn’t account for the difference you are currently seeing after a water change.

 

[optimisticdingo]

I found the same, Tropic Marin Pro Reef is not phosphate free. I found as much as 0.1ppm on freshly mixed TMPR using the Hanna ULR tester. However that wouldn’t account for the difference you are current seeing after a water change.

It's probably just due to the water being disturbed and it throwing the readings off

 

[LisaAP]

It's probably just due to the water being disturbed and it throwing the readings off

Possibly.

 

[Randy Holmes-Farley]

I'd check the water change water (raw tap water could do it, but not 0 ppm TDS RO/DI).

Otherwise, I'm suspicious that the result is test error.

 

[optimisticdingo]

I'd check the water change water (raw tap water could do it, but not 0 ppm TDS RO/DI).

Otherwise, I'm suspicious that the result is test error.

The water is 0ppm TDS RO/DI. I'm using the four stage BRS 150GPD system.

However, I've heard that plastics can release Phosphates and I store the water in plastic containers. Could this be the issue?

 

[Randy Holmes-Farley]

The water is 0ppm TDS RO/DI. I'm using the four stage BRS 150GPD system.

However, I've heard that plastics can release Phosphates and I store the water in plastic containers. Could this be the issue?

Possible, but not super likely, IMO.

Anyway, test the new water to see.

 

[optimisticdingo]

Possible, but not super likely, IMO.

Anyway, test the new water to see.

Sounds good I'll test