Diphosphonic Acid

[Miniguy77]

My newly replastered pool was recently filled using Jack’s Purple Stuff as a scale inhibitor. It contains diphosphonic acid which immediately added over 1,000 ppb of phosphates (my city water is phosphate free) as shown on a phosphate test. But apparently the kind of phosphates comprising diphosphonic acid are polyphosphates as distinguished from orthophosphates which are the known algae food. So two questions arise:
1. Are such polyphosphates also food for algae?
2. Do polyphosphates degrade to orthophosphates due to UV and other chemical action and over what period of time?

 

[jblizzle]

Calling @JoyfulNoise as the extent of my knowledge is that generally the phosphate levels can be ignored.

 

[JoyfulNoise]

Chlorine with eventually oxidize all polyphosphates and phosphonates to orthophosphate. Phosphate is a macronutrient (no so much a “food” as that is a crude analogy) for plant growth. As long as you keep your pool adequately chlorinated you can hold off on treating for phosphates until a more convenient time. 1000ppb (1ppm) realistically is not that high. Generally speaking, anything over 3000ppb should be treated but only if it makes sense (no input sources of PO4 being actively added to the water). I typically treat once per season if my phosphates are above 500ppb just to knock them down to zero. I have no input sources of PO4 so it sometimes takes two seasons to get phosphates higher than 500ppb.

 

[Miniguy77]

Thank you. What brands of phosphate remover are recommended?

 

[mattchase00]

If you are "Phosphobic" just terminate use of "Purple" and Phosphate reading will fall on it's own..

 

[Miniguy77]

I haven’t used any more of the stuff since the one quart used during fill, and I do not plan on using any more of it or any scale/stain inhibitor. But your remark is interesting. What is the chemical action that causes the phosphate level to decrease on its own?