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Unread 03/06/2018, 06:35 AM   #3
Dan_P
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Join Date: Aug 2014
Posts: 1,432
Quote:
Originally Posted by bertoni View Post
How are you measuring phosphate? Is this data from a total phosphate kit, or a standard orthophosphate test?
Hanna low range orthophosphate.

Here is an interesting observation. Holding the foamate solution at pH 3 for five minutes before neutralizing the solution and centrifugation (to clarify the foamate sample) increases the phosphate level. Ken Feldman thinks it might be a result of dissolving something inorganic like an insoluble salt or carbonate shell rather than hydrolysis of phosphate esters.

The results are definitely a head scratcher given the way skimmers work. I don’t know what is actually being collected by the foam. Besides arsenic, I have not found any information on substances that would produce false positives. Still looking and listening though. I am tempted to purchase the Hach total phosphate kit.


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