High Phosphate Levels

by Jennifer

My pool guy is treating my pool for high levels of phosphate and beginning black algae (YUCK). My pool guy has treated the pool for the phosphates but will treat the black/brown algae wednesday. He is not around today (sunday 7/24). My question... do we clean the filter now or do we wait until it is treated for the algae and clean it then?

Thanks for your help

Jen :)

Thanks for the question Jennifer

Be sure the pool guy has determined that you do in fact have black algae. Put a chlorine tab in a sock and place it on the spot. If it fades, it's algae. If it doesn't fade, put ascorbic acid (Vitamin C) in a sock and place that on the spot. If it fades it's a mineral stain and should be treated as such, with an ascorbic acid treatment.

I'm not sure what is meant by "clean the filter". What kind of filter is it? By the tone of the question I would assume it's either DE or cartridge. You always want to have a clean filter regardless of what's going on. Be sure he does the tests above so you're not wasting time and money. Look over the above posts about phosphate removers so you'll know what they do and don't do.

Hope this helps and have a great Summer. Let me know how it turns out for


Phosphate Question. What Range Should It Be?
by Rosa

The phosphate on my pool is 95 and the Leslie's pool shop lady told me that has to be around 300. My question is what is the right range?

Thanks for the question Rosa

First we need to establish what phosphates are. Phosphates are nutrients to help increase algae growth. The makers of phosphate remover products say the maximum level should be 125 ppb (parts per billion).

Most of the time pool owners get phosphates in scale and stain removal products. They're used for lifting stains, pool startups, and scale control. Many of these products contain phosphonic acid.

I have seen no evidence to support an increase in algae growth rates in swimming pool water that have phosphates below 1000 ppb. And I had a pool route in Arizona for years and was the pool operator for the YMCA in Albany, OR.

If you keep your chlorine between 2 - 4 ppm and the CYA between 30 - 50 ppm, and everything else in line, there's no need to use a phosphate remover. Phosphates are alright to swim in. The chlorine kills the algae, so if there's no algae, then why worry about phosphates? There is no correct range to keep phosphates. It can be 30 or 1000 ppb. It's not like your normal chemical readings.

Hope this helps and have a great Summer.


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