High Phosphates in Pool

[Rustom]

"For the past few months I have been fighing high phosphates in my swimming pool. I live in Northern California. The initial reading was 3000, however, after treating with PhosFree product the reading is sticking arount 300. However, each few weeks after the Phosfree treatment, the levels rises again to 1000 or 2000 within a week. My last test on Sat showed levels of 300, it is now thursday, and the level is already 1000. This is killing my wallet and I wanted to know is this a concern as I have no visible algae in the swimming pool. In additon, I do not have runoffs from lawns, landscaping or washing decks entering to the pool; no leaves or trees. What is causing the rise in phosphates and what should I do to prevent this from occuring. Note, all my other pool levels are perfect.

[chem geek]

If you maintain a minimum Free Chlorine (FC) level of 7.5% of the Cyanuric Acid (CYA) level (preferably try and target and FC of 11.5% of the CYA level), then you should not get algae even if the phosphates rise to 3000-4000 ppb. It may be that you would need a higher FC/CYA ratio at higher phosphate levels, but there aren't enough pool users with such high phosphates to know. Also, you can prevent algae via an algaecide such as PolyQuat 60 for a dollar or two per week and run with a lower FC/CYA ratio -- perhaps 3% of the CYA level.

As for what is causing the phosphates to climb -- I suggest you get the phosphates tested from another pool store or get yourself the Taylor K-1106 here. It is possible for fertilizer to be blown in if you live near a growing area -- even if it's not in your own yard -- but this seems unlikely.

Richard

[mr_clean]

If you have no algae problem and your chlorine usage is normal, then why are you adding phosphate remover?
These would be the two things you would be trying to stop, algae & chlorine being used up. There is no danger swimming in water with high phosphate levels.
How old is water in pool? If it has taken years for pool to get high levels that you now notice & just want to fix. A cheaper way to take care of problem can be to empty and replace water as long as theres no water shortage in your area.