Build-up starting on recently re-plastered pool

[tagyoureit]

Hi experts,

trying to figure out what's going on with my pool. In the beginning of the summer (June) we had our pool refinished with QuartzScape. We let it sit for until the middle of July before adding salt for our SWG. In the past 4 weeks I have already seen build up on the grout between the tiles. I'd really like to understand what's going on so I don't ruin the new tiles.

Pool: 39,000 gallons
Pentair Intelliflo VS pump; runs ~18 hours per day.
Pentair Intelliflo VS pump (for waterfall)
Spa overflows into pool
Solar water heating
Gas heater
Muriatic acid pumped into pool based on pH sensor readings

My readings with the TFT-100 kit:
FC 15 (I was away last week and am still learning where the SWG should be; I lowered it considerably when I got back.)
CC 1
TC 16
CH 375
TA 90
CYA 40
pH 7.6
Salt (per salt cell): 3670

for comparison, from my local pool store:
FC 6
TC 6
Salt 3900
CH 230
CYA 60
TA 110
ph 7.6

Would really like some advice on what to do so I don't get build-up on the pool.

 

[mknauss]

Welcome to the forum! :handshake:

Be sure to track CSI (Calcite Saturation Index). You want to keep it between -0.3 and 0.

With the test results it does not appear you should be getting much scale. Though you will always get waterline deposits. Could what you are seeing be efflorescence? Did the installers seal the grout or preferably use a silicone based grout?

Please add a signature. Read Pool School - Read This BEFORE You Post

Information in your signature will show up each time you post and it makes advice more accurate as we know what equipment we are dealing with.

 

[tagyoureit]

Thanks for the quick reply! I updated my signature. I do track my CSI... forgot to add it. It's currently -0.25. I'll have to ask the questions about the grout as I'm not sure on that.

It could be efflorescence. I do plan on trying to chemically/mechanically clean and and hope that it lessons over time (as I saw in some other posts).

-tag

 

[Rocket J Squirrel]

You said you “let it sit.” Have you been brushing daily?

Your sig didn’t show in your last post.

 

[tagyoureit]

"Let it sit" was slang for "not add salt until after 1+ month". And no, I haven't been brushing it daily. I have definitely not been brushing daily. Is that best practice for the first X months? I haven't read that anywhere on this site but could have missed it. I normally brush once every two weeks.

Not sure why my sig isn't showing. I saved it and "show your signature" is checked. Will see if it comes up this time.

 

[Rocket J Squirrel]

Your sig is there now, good work. I’m no expert on QuartzScape, but my understanding is that, in general, fresh plaster needs daily brushing such that the dust gets vacuumed or filtered out. For how long? Until you stop seeing plaster dust brush off. My recent plaster took about 6 weeks of daily brushing & vacuuming before it stopped. I have muscles that I never had before.

 

[tagyoureit]

It was brushed for about 4 weeks (almost daily) to get the plaster dust off. It has been brushed on the reduced schedule since then. The tile looked great for the next ~4 weeks (no buildup of any kind). It seems it's just since adding the salt that the buildup has been occurring, although I guess it could have been happening the whole time but is just more visible now.

 

[jeremycrook]

It was brushed for about 4 weeks (almost daily) to get the plaster dust off. It has been brushed on the reduced schedule since then. The tile looked great for the next ~4 weeks (no buildup of any kind). It seems it's just since adding the salt that the buildup has been occurring, although I guess it could have been happening the whole time but is just more visible now.

I have a couple tiles that seems to have some buildup, I was just thinking it was the salt. I have never tried to scrub at as I don't want to scrub my grout out, or anything. It's odd as its only one or so tiles the buildup occurs on.

 

[tagyoureit]

I did some cleaning last night. There is definitely some salt build-up and that comes up very easily. There was also some build-up that is happening just below the tiles and between the tiles that was pretty hard but came off with some scratching from my nails. The closest analogy here is like the "dots" candy I used to eat. And lastly is more of the slower, more distributed build-up that I have posted the pictures above. I do plan on trying to work on this with muriatic acid and possibly some mechanical scrubbing but don't want to do anything that will scratch up the tile unnecessarily/at all.