Pool Store Phosphate Testing

[Patrick_B]

Does anyone know what test they run at Pool Stores? I've never witnessed it there and I know it can't be a total Po4,
so what do they test for exactly, and what do they use?

 

[heythatguy]

I use an aquacheck phosphate test. It can test up to 1000ppb. I left work so I cannot tell you a test or model number on it. Comes with a powder packet you empty stomach into a small tube add pool water, shake, turns blue depending on amount of phosphates. I have noticed that the tube will turn blue over time. When you look the results you look down the tube and compare it to a chart.

 

[Patrick_B]

Thanks heythatguy, that tells me something for sure. Just curious, do you work for a Pool Service/Pool Store?

 

[heythatguy]

Yes I do. I know there are strip tests out there, never used them. I don't know what my competition uses, i've seen them called lps on here.

 

[JamesW]

The most likely test is the molybdate test, in which phosphate combines with added molybdate, which is then reduced by ascorbic acid or stannous chloride to give a blue solution. The intensity of the blue color is proportional to the concentration of orthophosphate (PO₄^3-).

 

[heythatguy]

JamesW nailed it. I was replying from my phone earlier, so I didn't say all that I wanted, the tube turns blue over time so I'm sure that can skew the results and then it is subject to the person that is reading the test. I've had a customer with 1000+ ppb phosphates, somehwer around 40k gallons, took 5 qts, of hasa phosout, removes 1500ppb in 20k gallons, but that did get him below the 200ppb phosphate level, and it has stayed down to, saw him a week ago and tested his water. Just be diligent with the products they try to sell you to remove phosphates. Some by the natural chemistry are weak, 600ppb in 20k gallons, like i said the hasa 1500 ppb, seaklear has one at 3000ppb in 20k gallons, and they have a commercial line the will remove 9000ppb but it will also remove a good portion of your wallet.

 

[JamesW]

In my opinion, unless you're getting a lot of phosphate scale, then you do not need to worry about phosphates.

Chlorine will keep algae completely under control regardless of phosphate levels.

I wouldn't even bother testing for phosphates unless you were getting excessive scale that could not be explained by calcium carbonate.

Note: This reference seems to indicate that calcium phosphate scale is not likely to occur unless the pH, phosphate and/or calcium levels are very high.

http://msdssearch.dow.com/PublishedLite ... age=GetDoc

 

[Patrick_B]

No James I am not concerned with it at all. I see the Pool Store results for it and just wondered what they use. I treat and test water
at work and was just curious. I figured it was a simple Ortho test of some kind. I completely agree that Po4 is totally irrelevant in pools.
Thanks very much for your reply.