Can't stop pool stains

[kichi]

Hi all,

I am a relatively new owner of a 40 year old pool. I have been following the BBB method, but am having trouble preventing the pool from staining. There have been a number of new stains that have developed in the last 4 months since I bought the house (most look like dirt). I have kept my FC at shock level for the last 2 weeks, but there has been no reduction. And I got a new purple stain in the last 2 days (the only new thing I did was add borax to raise pH). My calcium level is low, and I am traveling for the next few days so I was trying to get the pH up to control my CSI.

See attached pics. Here are my latest test results.

FC: 12
pH: 8
TA: 100
CH: 150
CYA: 30
Inground Gunite pool

Thanks

 

[duraleigh]

The pictures are too vague for me to get a good opinion, but the stains that look like dirt (and won't brush off and are rough to the touch, right) are likely calcium scale.

Your pH is too high. (and that is the big contributor to calcium scale) Pool School gives ranges for all the parameters.....you should review it and get your pH into the seven's.

Your other test results look fine.

I have no clue on the purple stain. Have you added some ingredients into the pool that you haven't mentioned?

 

[kichi]

I will try and upload better pics. I was getting an error saying the size is more than the limit.

My ph was 7.2. At my current chemical levels and water temperature of 54, the CSI was - 0.75. I increased my pH to get CSI greater than - 0.6. Should I have not done that? The issue is my CH level is low, and I am traveling, so won't get a chance to raise that for the next few weeks. So I have to pick the lesser of 2 evils (high ph or low CSI). What should I do?

 

[duraleigh]

What should I do?

Ignore CSI and use the guidelines we suggest in Pool School. CSI is useful in some pretty rare instances but yours is not one of them.

Keep your pH in the seven's.......that is a pretty hard and fast guidline.

 

[kichi]

Thanks. That's good to know. I think you are right about the calcium scaling since I also saw some white residue on the tiles. Now that I think of it, the first time I checked the chemicals in my pool after I bought the house, everything was fine except for low calcium. And all these problems have started since I started trying to increase my calcium. When I get it above 250, it goes down soon after that and I start seeing more stains. Is there a possibility that the right level for calcium in my pool is lower than 250 (as recommended by pool school)?

 

[Rocco]

I had purple stains at the end of the 2012 swim season. This was due to copper in the water. I was using a copper based algaecide which was adding copper to the water, it can also be caused by a mineral cartridge. One evening I shocked the pool and left the pump running, however a short time later we lost power for about 13 hours so the pump did not circulate the water. The next morning there were large purple stains on the bottom of the pool where the the shock had settled.

There are a couple of things that i had on my list to try. The easiest thing I found was to get some ALUM from the spice aisle in the grocery store. If you can put this in a sock and set it on the stain it should remove it if it is a copper stain.

The other was to get some powder acid and place it in a sock on the stain for a few minutes as well. This should work with most stains.

However neither of these options will actually remove the metal from the water, if your purple stain is in fact caused by metal in the water.

Hope some of this helps.