Hello, I have some stains that I think might consist of calcium. I also know I have a small amount of yellow mustard algae, but my plan with that is to do a minor shock to the pool to fix that issue.
My main concern however is the stained dark splotches that I have on my pool walls and floor. I did some of my own research and realized that the potential fix is called a "Low Alk Treatment". I would reduce the PH to a low amount, possibly around 2.0, while keeping the TA down in the 20-30 range, and let it do that for about 48 hours.
However, is this even my problem based off the pictures you guys can see, or is it a different? Essentially every time I try to brush it, it won't come off, so I'm figuring it's embedded "underneath" the plaster, like a moisture of some sort. As soon as I bring the ph and alk to a low level, the plaster does a chemical reaction to "release" it, and then I use my pool pump/filter system to draw in all that stuff, cleaning it out about every 12 hours for 48 hours.
Now is it recommended to leave the pool pump running for 48 hours on the ENTIRE process of the low alk treatment, or just when I need to collect the released contents from underneath the plaster's surface layer? I've had this pool since 2006, and have had a small but steady buildup of the stuff shown in the pictures (the dark grey/light grey splotches, not the yellow). Another thing that I notice is that it is MUCH more visible to see the splotches and stains when it is cloudy and when it is not in direct, bright sunlight. It becomes less noticeable when it is sunny and bright without hindrance (aka no clouds, etc).
The pictures are taken when it is bright and sunny, it was cloudy yesterday but I did not manage to get pictures then. I would say that the problem I have isn't enormous like what I've seen with other people's problems, but it is definitely an issue that I need to get fixed.
Thanks, and appreciate any help in advance!
Please keep in mind that when it is cloudy it looks more grey-ish then it does now.
Better pictures of the overall problem (taken during late day): http://imgur.com/IPUjyMj,33jUEkE#0