Ask The Pros Swimming Pool and Spa Help and Information

Problem keeping a chlorine level up

Q: Hi: I have a Waterway in-line Chlornator. Installed July 2007, white, gray lid, gray control knob on top of return line(not the older type). Pool is in central Florida, 7,500 gal, 1 1/2 hp pump,no screen. The first weeks the chlorine level stayed up/too high. I adjusted it down, also cut hours on pump to 5. I can't get the chlorine back up. Am adding by hand every other day/summer, 3rd/4th day now that its cooler. Any chance it is a defective unit? Suggestions?(can't afford to go salt) My warranty is expired, should have checked into this sooner. Thanks.

A: I would have a few questions for you regarding the diagnosis. Think about these and things should become clearer.

Do the tablets dissolve? At the end of the day all the chlorinator really does is run the water over tablets.  If the tablets are dissolving at a reasonable rate, then the problem is most likely elsewhere.

Where do you get your tablets? We find that many of the tablets sold through large retailers (Wal Mart, Costco, etc.) do not have a lot of active chlorine.

What is your cyanuric acid level? Cyanuric acid and chlorine level are intertwined and it is a good thing to know.

How are you testing it? Sometimes the test can be fooled by high levels.

If all the above seems normal and all the other pool readings are normal we would run a test for phosphates. A high phosphate level will "eat" chlorine quite effectively.

We have a more detailed discussion of some of these issues in our chemistry section. Check the link below:

Pool Water Chemistry Guide

Let me know what you find.

Questions About Chlorine Free Pools

Q; We are using Sea Klear clarifier. We thought we didn't need chlorine or bromine with this system. Can we use Nature 2 as the sanitizer instead of Chlorine or Bromine? We are disappointed with chemicals in our hot tub and we are looking for something natural.

A: Clarifier is simply a device to make pool water clearer, it clumps together particles so the filter can catch them easier. It has no sanitation function for keeping the water clean. You can  use Nature 2 or the Poolfrog to do some organic control but both of them require a chemical backup as well. The only system that I know of that is completely bromine or chlorine free is the Cl Free System. You can read some information about it at the link below:

Cl Free Chlorine Free Pool/Spa Information

There are some other strategies for making a pool very low chlorine, but only one for chlorine free.

Green Pool with Phosphates and Low Cyanuric Acid Levels

Q: I just got back from a pool store who did the pool analysis and said I had 400 part per million of phosphates in my pool.  I have been away for business and now the pool is green.  The cyanuric acid is also around 20.

I have the zodiac dual clear system with the nature cartridge and the salt chlorinator.  I have a 20000 gallon pool.

What do you recommend?  My chlorine levels are zero and only move up a bit during the night.

A: Phosphates are normally measured in parts per billion. So if you have 400 ppm that would be extremely high, lets assume they mean PPB. You do want to pull out the phosphates, I would use 8 oz of Phosphate remover:

SeaKlear Phosphate Remover

You do not have enough cyanuric to stabilize your chlorine in the sunlight, I would get yours up to about 80 ppm. Add 10 pounds of cyanuric acid to your pool. This should help you hold chlorine in the water and take some stress off of your salt unit. If the cyanuric is getting low, have you checked the salt level lately?

Q: Can I buy the cyanuric acid too?

A: We have shipping issues with the cyanuric, any of the pool stores up there should have it. They sometimes call it conditioner.