Plaster Surface Issues (With Pics)

[ScottFL]

Hello,

Purchased a house last September, and I have been taking care of the pool since we bought the house. I have been through pool school on this site, and I thought my levels are generally good. I've noticed that the plaster is starting to get "rough spots" in certain areas, and I'd like to know why. It seems to be progressively getting worse (More affected areas). I will say that some of it was there when we moved in.

 

[JVTrain]

Also are the areas in your opinion spots of erosion (lower than the rest of the surface) or scale (higher than the rest of the surface)? To me it looks like erosion.

Picture 1: Base of step riser and back of step tread in shallow end?
Picture 2: Location? Wall? Floor? Near any feature like skimmer or return?
Picture 3: Assuming a floor drain? or wall drain?
Are any of them in an attached spa area or just in the pool?
What type of automatic cleaner do you use if any?

 

[ScottFL]

From this morning:

FC: 7 ppm
CC: 0
CH: 325
TA: 90
CYA: 50

Most seem to be areas of erosion. There is quite a bit in the shallow end that's just on the pool floor. I've attached a rough drawing of where these sections are located in red. We don't have a spa or use an automatic cleaner. I just use a brush. Also, not pictured is the skimmer which is to the right of the steps.

I guess my main concern is the number of affected areas seems to be appearing rapidly (in the last year)

Thanks for your help!

 

[JVTrain]

Your numbers don't seem to indicate a problem with corrosion or scaling even over a wide range of pH (7-8.2). Are you having to add acid to the pool to combat pH rise at all? Are you adding the acid very slowly and brushing the pool after adding? Are you manually chlorinating with bleach or a SWG?

 

[ScottFL]

Your numbers don't seem to indicate a problem with corrosion or scaling even over a wide range of pH (7-8.2). Are you having to add acid to the pool to combat pH rise at all? Are you adding the acid very slowly and brushing the pool after adding? Are you manually chlorinating with bleach or a SWG?

Recently, we have had some rain, so I really haven't added any acid to the pool. I when I do, I try to add the acid in small increments, in the deep end. I guess it's possible I have brushed after adding acid. I'm manually clorinating with this stuff: Shop Kem-Tek 1-Gallon Liquid Pool Chlorine at Lowes.com Probably three months ago I noticed my CH was lower than it should be (so not by a lot) and have added Calcium Chloride to bring it up some. Father-in-law has a pool and bought us a bunch of the "pucks" when we moved in. I don't really care for them, because they are expensive, but we have bunch so we are using them up.