Brownish-gray stains in vinyl IG pool

[JohnT]

My first thought on seeing the picture is they are marks made by leaves laying on the bottom.

[gumbeaux71]

Thanks all for your input. Those stains could indeed have been caused by leaves as the pool basically sat during the winter months. It was covered, but there was still some debris in the water when we uncovered. Also, I was just seeing the beginnings of mustard algae, so I used some Yellow Treat, brushed, shocked, and ran filter appropriately.

My pool's PH generally stays around 7.4 - 7.6. However, I read in a couple of places that the PH should be lowered and chlorine discharged (used up) before using ascorbic acid. At the time of my post, I really thought this was some kind of stain caused by metal, but trying the ascorbic acid didn't help. That's when I figured it was a non-metal stain. However, I am pretty certain it's not black algae, as I had dealt with a few spots of that in my spa a few years ago.

To make a long story longer, I shocked last night and the stains seemed much, much lighter this a.m. I'll continue that route, I guess.

I will post my numbers when I get home and test the water. I'm still puzzled as to what caused such bad staining. I guess it could have been leaves...

[gumbeaux71]

Hi Dave,
Here are my numbers from this evening:
FC .5
CC 0
TA 90
CYA 40
Ph 7.2

I shocked to 10ppm last night. You are right that something is eating up my chlorine!

[smallpooldad]

Dave,

I had the same problem. My pool is gunite - 9,000 gals.

The ascorbic acid ( 1 lb in my pool) treatment outlined by Maria (Mbar) in one of her posts only worked when I got my ph down to 6.0. Use Ben's program to see what your acid needs are for your size pool. No damage was done to the pool, but boy did it look great after the treatment.

Make sure your chlorine is at zero before you start or all you will be doing with the ascorbic acid is useing it up to eat the chlorine and not cleaning the pool.

As ascorbic acid puts the iron/calcium into to solution and does not precipitate it is important that you use an agent such as metal out ( 3 quarts in my pool ) to get it out to your filter. If you have a sand filter (mine is 300 lbs), then put in 1/3 lb to 1/2 lb of DE to help it get trapped. I use the blue stuff it helps precipitate the metals.

If your filter clogs run the backwash for a minute, no longer, as you want to keep the filter heavy on the DE to trap the metals. The best solution would be to completely drain the pool after 24 to 48 hours as this would take out all the solution.

Hope this helps.

[smallpooldad]

Dave,

Sorry forgot one thing. Ascorbic acid eats up the chlorine and if you are not emptying your pool you will need to add A LOT of chlorine, before it takes. If you used Algaeside 60 you might get a false reading stating you have no chlorine when in fact you do, this will go away after 24 to 48 hours.

Aloha