Quote:
Originally Posted by bertoni
How are you measuring phosphate? Is this data from a total phosphate kit, or a standard orthophosphate test?
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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.