New user with old vinyl pool

[markwg]

First post

Thanks for your response. I do check for stabilizer, and added some this spring. I had ask about using metal free when I agreed to install the frogger, and was told it would not be a problem. So, a contradiction but I believe you and will stop using the metal fee. I live in the country with fields front and back, and was told that farmers spraying was probably the source of the phosphates. I have a test kit and check for phosphates every week.

Couple questions please;
Do I need to chlorine shock every week? If so, can I use non-chlorine shock, or alternate between the two?

I have some yellow stains on the white portion of the liner above the water line where it meets the coping.
Any suggestions about how to remove them?

Thanks -

[PoolDoc]

+ Do not use non-chlorine shock. It's expensive, screws up your chemistry, and is only marginally effective.

+ Test your stains with Vitamin C tablets and with Iron Out. See if place tabs or a small pile of I-O will remove the stains. Let us know.

+ Check your fill water for phosphates. Most utility water has some added phosphates, but it's possible (if not likely) that well water might have it, too. Phosphates from farm fields? Not likely, unless you are ALSO getting a bunch of blown dirt and dust.

+ FYI, I just Googled "pool frogger" and didn't find anything with the word "frogger". I was assuming that you have the King Technology pool "FROG" feeder system?

+ As far as we can tell, people selling mineral systems ALWAYS say that the copper won't be a problem. Occasionally, they are even correct.

+ What is your stabilizer level? How did you test? Are you aware that test strip CYA measurements are usually HORRENDOUSLY inaccurate?

[PoolDoc]

Mark, I deleted re-quote, since there was no post. Not sure what you intended.

[markwg]

I added stabilizer according to what the pool store tested and said I needed, 2 lbs. I am having a recurring problem I thought I had cured. I keep getting large areas of grey/or brown stains on the pool floor that do not brush off. Not spots. They clear up when I shock, and after a day I vacuum to waste the residue from the pool bottom. So, algae I assume.

Battled this all last summer. When you told me about the metal free working against the copper in the Frog system, I figured that's what
the problem was. But I have discontinued the metal free and just had it happen again.

The water looks great and tests fine, and I have been testing for phosphates also. Thanks for your help.

[PoolDoc]

As far as I know, all forms of algae can be brushed off. And, metal stains would get worse, not better, when you shock.

Could it be fungus bleed-through? That's the only thing I can think of that would behave the way you describe.

If the ground is damp on the non-pool side of the liner, dark fungal or bacterial colonies will sometimes form next to the liner. The pigment from these will penetrate the liner, and show up on the POOL side of the liner. Very high chlorine levels will bleach out the organic pigment, but only on the surface of the liner. The only solution is to (a) dry out the ground under the liner or (b) treat the area with high levels of an persistent anti-fungal, like a mixture of borax and copper sulfate.

I won't ask you to photograph it since when I've seen it, it was never something you could photograph, unless you have underwater gear and high quality off-camera underwater lighting or flash. But, you might swim down with goggles and take a look -- it has roughly the same color as fungal staining on an old white towel.

Let me know what you find.