Low Ph And Staining Help!

[Pete Rittwage]

I am a relative beginner to pool chemistry. I bought a house 2 years ago with a 21' round old above ground pool with a new liner. I am able to shock and use algecide to get rid of algae and get the water clear, but this year when I opened the pool (Georgia, Southeast USA) my kids said the water "tasted funny". Not that they should be tasting it, but...

Anyway, I tested the water and Ph was low off the scale. The test shows light yellow (below 6.8). I bought a 10 pound bag of Arm and Hammer and added a pound at a time over the weekend until it was gone, but it only turned a little darker yellow on the test. The TA test shows about 50.

However, even with the still low Ph, when I added the baking soda, the bottom and sides of the pool stained badly. Ugly yellow steps (were white as snow) and an ugly yellow ring and ugly yellow stains all over the bottom. This stain will go away when rubbing Vitamin C on it, but it comes back the next day. It is not orange or brown.

Should I be getting this staining even with the Ph that low? I lowered it back down to see by putting in a pound of Ph reducer, and the stains went away again, but this can't be good.

I also let the Chlorine go to 0 and put in two quarts of Metal Out and ran for a couple days, then raised the Ph back up, still ugly stains came back.

What am I doing wrong?

[imnay]

I am a relative beginner to pool chemistry. I bought a house 2 years ago with a 21' round old above ground pool with a new liner. I am able to shock and use algecide to get rid of algae and get the water clear, but this year when I opened the pool (Georgia, Southeast USA) my kids said the water "tasted funny". Not that they should be tasting it, but...

Anyway, I tested the water and Ph was low off the scale. The test shows light yellow (below 6.8). I bought a 10 pound bag of Arm and Hammer and added a pound at a time over the weekend until it was gone, but it only turned a little darker yellow on the test. The TA test shows about 50.

However, even with the still low Ph, when I added the baking soda, the bottom and sides of the pool stained badly. Ugly yellow steps (were white as snow) and an ugly yellow ring and ugly yellow stains all over the bottom. This stain will go away when rubbing Vitamin C on it, but it comes back the next day. It is not orange or brown.

Should I be getting this staining even with the Ph that low? I lowered it back down to see by putting in a pound of Ph reducer, and the stains went away again, but this can't be good.

I also let the Chlorine go to 0 and put in two quarts of Metal Out and ran for a couple days, then raised the Ph back up, still ugly stains came back.

What am I doing wrong?

I want to be sure I understand what you are doing.

If PH is low you DON'T add sodium bicarbonate (Arm & Hammer from the grocery) you add Soda Ash to increase PH.

If the Alkalinity is low that is when you add sodium bicarbonate (baking soda) to raise Alkalinity.

I remember like the second or third year we had our AGP and I got the two mixed up and my PH was very low and I kept adding pounds and pounds of Arm & Hammer and finally my bride saw what I was doing and fixed things right up by adding the right stuff. Now we buy both Soda Ash and Baking Soda in 50 lb bags from the local hardware store - cheap, cheap, cheap!!

Beyond that in just our simple experience of over 20 years low PH - including VERY low PH has never caused any stains on our liner so we can't imagine what else is going on but I am sure some Subject Matter Expert (SME) will post the right answer soon.

GoodLuck

[chem geek]

I answered to a duplicate thread here basically with the same advice you gave and I too am stumped by the staining at lower pH unless the metal content is extremely high.

[chem geek]

If PH is low you DON'T add sodium bicarbonate (Arm & Hammer from the grocery) you add Soda Ash to increase PH.

If the Alkalinity is low that is when you add sodium bicarbonate (baking soda) to raise Alkalinity.

Now I am TOTALLY confused because the advice above is correct, but in other posts you are saying that you use baking soda to raise the pH and soda ash to raise the total alkalinity.