High Phosphate Levels And Low Chlorine Issue...

I have an in ground chlorine pool approx. 25,000 gallons. I have high phosphate levels and some level. I have 0 chlorine in my water, however, my cholorinator has tablets in it and it seems to be functioning correctly.

I have a history with phosphates and know that it is the cuplprit to my chlorine issue. I do have some issue with algae now. I put in some algae treatment on Saturday AM after we vaccumed and swept pool. Saturday night I put in two 48 oz. bottles of PhosFree as directed.

Today is Monday and I still do not have any chlorine in my water and algae is coming back. HELP me before I drain the darn thing and fill it in with dirt!!!

Thanks for the question

I had another question about phosphates that I answered in this post:

Swimming Pool Phosphate Level Over 1000

Basically, phosphates are food for algae. Many people believe that they need to keep the phosphates down by adding Phosfree. This is to remove the phosphates. But, if your chlorine level is kept between 1.5 - 3.5ppm, then there will be no algae, so it really doesn't matter what level the phosphates are.

The post above explains that in a little more detail. First, you need to shock with Dichlor. This is a fast acting chlorine with a stabilizer (cyranuric acid/CYA) in it. You'll want to get your CYA between 30 - 50ppm.

Use a Taylor FAS-DPD K-2006 test kit. It's the best and the one most pool professionals use.

Water Testing Kit

Pool Water Testing

No Free Or Total Chlorine In The Pool!

Pool Chlorine

Chlorine Tablets

The chlorine tab page has the Dichlor information you need and the chlorine page has a chart for shocking your pool. The question says you used an "algae treatment". I will assume this is an algaecide. Remember that algaecides are used for preventative maintenance only. They're not going to get rid of an algae problem or green pool water.

While you're shocking the pool, the algae will be eating up the chlorine so you'll need to manually dose and test your pool each day. Try to keep the chlorine level up around 8ppm while this is happening. You can also use a good PolyQuat 60 algaecide as an insurance policy for algae while you're going through the shock process.

This contains no copper or other metals and is safe for vinyl pool liners. Make adjustments at night, allow for a complete turnover of the pool water. This is normally around 8 hours, retest, and make another adjustment.

The algae will turn a white/grayish color. Brush the walls and floor the best you can to loosen up algae that might be sticking. And backwash once per day. You want to keep the filter cleaned out. And keep an eye on the pool water level. You'll be backwashing and losing some water.

The water level should be 1/3 - 1/2 from the bottom of the skimmer.

Swimming Pool Algae

Green Pool Water

Once everything is stabilized there should be any need to add Phosfree because you'll have a constant stream of chlorine in the pool to kill bacteria and algae. Hope this helps and have a fun and safe swimming season.


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Swimming Pool Phosphate Level Over 1000

by Linda
(Cape Coral, FL)

We bring our pool water in to be tested every week. Suddenly the last 3 weeks the phosphates are thru the roof (Pool guys words) and has us adding a product to lower it.

Have done this three times...they checked the house water..say its good..


Can chlorine affect the level??? We are soooo confused and yet, the pool is crystal clear!!!

Great question Linda

Algae needs phosphates and nitrates to reproduce, grow, and spread. So basically phosphates are food for algae.

You get swimming pool algae and green pool water when the swimming pool chlorine level is low. You always want to keep your pool chlorine level between 1.5 - 3.5 ppm and your cyanuric acid level (CYA) between 20 - 40ppm.

Adjust Your Swimming Pool Chlorine..Swimming Pool Chemistry..Swimming Pool Care.

Swimming Pool Chlorine..Chemistry..Above Ground Maintenance..Care..

Your pool guy is telling you to add some kind of phosphate remover. One of the more popular kinds is named Phosfree. A 32oz. bottle will normally run about $32, basically $1 per oz.

You can get a test kit for phosphates. This kit normally runs about $12 and is very easy to use. You simply fill a vial with pool water, put a pill or dry mixture in the vial and shake it for about 1 minute. The water will turn a shade of blue, then you match the blue pool water with the comparison chart provided in the kit.

White or very light blue indicates a low phosphate level and a dark blue indicates a high level of phosphates.

I'm not a big fan of phosphate removers. I think they should only be used in extreme circumstances and here's why.

Your pool chlorine is the sanitizer for your pool, meaning it kills the bacteria and organic matter in the pool, including pool algae. This matter is then trapped in the swimming pool filter and is backwashed away. This is a fact that all pool guys will agree with.

When your swimming pool chlorine is the right level, between 1.5 - 3.5ppm then there shouldn't be any swimming pool algae, right?

If the pool chlorine is doing its job in killing this organic matter, and there's no pool algae, then why should you worry about the phosphate level? There's no swimming pool algae to eat up the phosphates because the pool chlorine is killing the algae on contact.

The YMCA pool that I still operate has a slightly higher phosphate level but it doesn't concern me because I keep the chlorine level between 3.5 - 4.5ppm. We've never had a pool algae outbreak or green pool water because the pool chlorine level is always kept at optimum range.

You can keep your pool crystal clear by uses the techniques found here:

Swimming Pool Tips..Maintenance..Above Ground..Inground..Care

Swimming Pool Chemistry..Care..Inground Maintenance..Salt Water..Weekly..

and throughout this website.

Hope this helps and answers your questions

Good luck with your pool


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