Phosphate testing

[Reefer1978]

Orthophosphate is the inorganic type, and all of our hobby kits test that one. It’s also the one that would potentially inhibit calcification.

Hanna tests orthophosphate, changes the value into phosphorus (still the same inorganic type), which can be converted back into phosphate ppm. It’s always using the inorganic form, and that’s fortunately the most prominent form in reef tanks and the most important to test IMO.

It’s just unit conversion, like changing mL to L or gram to kilograms.

Thanks @Miami Reef . If all of our hobby kits are testing Orthophosphate, and that's the one that would potentially inhibit calcification, why is it important to get this reading up if it's very low, considering other forms of phosphorus are present in the water? ICP says my phosphorus is very high, but per hanna, it should be even higher. I am really confused by this one.

 

[Tikki]

I would recheck with a test kit anytime I see something surprising on Hanna or icp.

 

[Dom]

I am running into an odd issue with testing phosphate with Hanna Phosphorus Ultra-Low Range Checker (HI736). A few months ago I received a new pack of reagents, and my Phosphorus reading was getting lower and lower, until is stabilized at 16 ppb (about 0.05 ppm). I wasn't too concerned at this stage, figured I must be doing something right. But, cyano started showing up at some point, which got me concerned.

I sent away ICP test, (Triton), which confirmed my suspicion that Phosphate is indeed higher then Hanna is recording: ICP returned on July 2nd with:
* Phosphorus 96.00 µg/l
* Phosphate 0.294 mg/l

I contacted Hanna Instruments team who right away suggested it may be a bad batch, and sent me replacement reagents. They came in last week, new water test gave exact same reading as before --- 16 ppb (about 0.05 ppm).

Who do I trust?

Have you compared the LOT numbers on the original and replacement batches?

I just received a new package of Hanna UL reagent and wouldn't mind knowing the LOT number on your bad batch.

 

[Reefer1978]

Have you compared the LOT numbers on the original and replacement batches?

I just received a new package of Hanna UL reagent and wouldn't mind knowing the LOT number on your bad batch.

I thought it might be the LOT itself, so I contacted Hanna and got a fresh one straight from them. Readings were identical.

 

[Miami Reef]

Thanks @Miami Reef . If all of our hobby kits are testing Orthophosphate, and that's the one that would potentially inhibit calcification, why is it important to get this reading up if it's very low, considering other forms of phosphorus are present in the water? ICP says my phosphorus is very high, but per hanna, it should be even higher. I am really confused by this one.

This may help. It’s a thread I made last year that Randy responded to.

https://www.reef2reef.com/threads/do-corals-prefer-orthophosphate.1081060/

 

[Reefer1978]

A friend of mine just to buy with his checker…

 

[Reefer1978]

@Randy Holmes-Farley or @Miami Reef could you guys please double check my math cause I am being really dumb on this one. NeoPhos says 1 ml produces in 1 us-gallon .25ppm. I am trying not to raise too quickly, is my daily dose of 4ml enough?

 

[Miami Reef]

@Randy Holmes-Farley or @Miami Reef could you guys please double check my math cause I am being really dumb on this one. NeoPhos says 1 ml produces in 1 us-gallon .25ppm. I am trying not to raise too quickly, is my daily dose of 4ml enough?

What’s your tank volume?

 

[Miami Reef]

@Randy Holmes-Farley or @Miami Reef could you guys please double check my math cause I am being really dumb on this one. NeoPhos says 1 ml produces in 1 us-gallon .25ppm. I am trying not to raise too quickly, is my daily dose of 4ml enough?

If your tank is 200 gallons, 4 mL will increase PO₄ by 0.005 ppm.