Pool tile scale and RO purification

[MBPooldiy]

As a TFP convert of a few weeks (after discontinuing my pool service) I've made a lot of progress with my CYA/high pH pool. CYA is coming down via backwash and soft water refills. (But no measurable decrease in CH yet.) Yesterday for the first time I was able to get my CSI index below .3. This happened after being advised by a TFP member to work on lowering my TA, which I've been doing by adding some significant amounts of acid, which also lowered the pH to levels I don't think my pool has ever been adjusted to in the past. We have a significant calcium ring, which I want to have cleaned and then never have to deal with that again.

I had planned on having an RO treatment to quickly resolve my high CYA and CH, followed by having my pool tile calcium cleaned. The service that does the cleaning does not use glass beads so I think they will be using Kieserite. It is advertised as being safer than glass beads and they guarantee there will be no tile damage whereas companies that use glass beads do not guarantee that. I have read on this site that Kieserite dissolves in water and may increase sulfates which can cause scaling which is even harder to remove. I am wondering now if I should do the tile cleaning first and then the RO treatment. Does controlling CSI prevent all scaling or only scaling associated with high calcium? Is there a test for sulfate levels?

Test results as of yesterday evening:
FC 15
pH 7.4
TA 140
CH 600
CYA 140
salt 930
temp 88 deg
CSI .26

 

[JoyfulNoise]

Do the tile cleaning first then the RO.

I have had tile cleaned with kierserite. It is NOT benign as they advertise. They love to say - “It’s even safe for plants and landscaping!” But it is magnesium sulfate and you will get dissolved sulfates in the water. That is not good long term for your SWG. And yes, gypsum scale (calcium sulfate) is way harder to remove than calcium carbonate.

Tile scale is a fact of life here in the desert. Your pool will develop it no matter what; it’s only the extent of it that you can control. Figure you’ll need to clean tile every 3-5 years. Or you can let it build up and just clean it when you sell the house.

 

[MBPooldiy]

Thanks, I just rescheduled it. I sanitize my pool with LC--just updated my signature. If I leave the calcium deposits does it ever get to a point where it can damage the tile and/or get more difficult to remove?