White plaster discoloration

[Boudreaux]

My pool with white plaster is about a month old. I have noticed when it is overcast that there is a browning discoloration look to the plaster. It looks like there is dirt on the bottom of the pool. When it is bright you don't see it. This started in the shallow end but is making its way to the deep end. My test for minerals was negative and I keep the other levels well within range. Is this a normal occurrence for white plaster?

 

[Guest]

brown is usually either iron or calcium scaling. Try holding a vitamin C tablet on the stained area. If the stain disappears under where you held the tablet in about 30 seconds it's iron.
I know you recently had or still have a problem with water that turned color after shocking (indicative of metals in the water) and that you have a SWG. If food grade salt was used in startup (some builders do this) it contains iron salts that can cause staining.
Putting this all together I would say that your pH has been spiking and that you have metals in your water. Please post a FULL set of test results and, if possible a pH history (how high it rises before you add acid to lower it and how often you have to do this.)

 

[Boudreaux]

Here are my last full results as of 8/26
FC - 5.0
TC - 5.0
pH - 7.6
TA - 120
CYA - 90
CH - 225
TDS - 1700
Copper - 0

Here is my pH history...
8/24 - 7.4
8/23 - 7.6
8/16 - 7.4
8/9 - 7.5
8/8 - 7.5
8/1 - 7.5
7/29 - 7.5
7/26 - 8.0

The pool was filled on 7/24.

The green color did go away. One person I talked to said it may have been I called the shock to soon after adding the calcium and the reaction could have caused the color but that was a different topic.

I will get my CH up to 300 but other than that I think all other levels are good except for the CYA being a little high.

Thanks for the help.

 

[Guest]

Try the vitamin c tablet on the stain and report what happens.