Stumped by persistent algae

[PoolDoc]

You have 3 options:

1. As Watermom explained, you can operate with high CYA *if* you have high chlorine, possibly 15 ppm normally and 30 ppm while cleaning. BUT, you must be able to test accurately to do so.

2. You can drain and refill. I don't know how much you need to drain: usually a CYA reading of 100 *actually* means, "100 or higher". Your actual CYA may be 200! If you have a vinyl pool, this isn't really an option. Even with a fiberglass or concrete pool, it's not an option if your pool in level damp ground -- pools can literally float out of the ground.

3. You can add borax to reach 60 ppm, and phosphate removers to get PO4 < 125 ppb. This can make it much easier for the chlorine to kill the algae. But lowering phosphates can be difficult, since you may have high phosphates in your fill water, AND you may be in the habit of adding pool chemicals which CONTAIN phosphates!

[ucrazy51]

Thanks for the comments, I've started with some partial water changes and after of week of this the pool is at least nice and blue now. Chlorine is at 0 but CYA is still at least 100. I'll continue the water changes and start dosing with some chlorine. Recommended test kit has been ordered. Should I use any stab. tabs in a floater. Thanks again for the comments.

[Watermom]

No, you don't need any more CYA which is what stabilizer is. Yours is already too high which is why you are doing the partial water changes.

[ucrazy51]

Got it, thanks.

[PoolDoc]

Don't wait; start dosing with chlorine NOW! It is much, MUCH easier to avoid algae, than to clean it up. A single algae episode can consume a month's -- or in bad cases, a season's -- worth of chlorine!