Rough surface on recently re-plastered pool

[hlarsen]

Hi all, we recently moved into a new house that has a combo pool/spa with a spillover. The pool was replastered 05/22, so about three months before we moved in. I'm not sure who did any initial chemicals and/or 2x daily scrubbing the pool, which I've read are needed for new plaster. We've never been pool owners before so I set myself up with a TF-100, Pool Math, and have been reading the forums. I had a pool tech come by to review our equipment, he thought it was about 13k gallons, though the previous owners were not sure. From working with Pool Math chemical values I'm thinking it's somewhere around 10k-13k but I should have a better number soon now that I have some proper measuring cups for chlorinating. Upon move in the water looked fine; testing with a TF-100 was showing low Chlorine/TA/CYA and high PH. After a few weeks of testing adding chems the levels look ok to me.

The surface of the pool is pretty rough, not a huge problem for adults but our young children have been getting blisters and cut up feet after swimming. They're in there for an hour plus so I'm sure that has something to do with it, but my wife had the kids at a public pool recently (with a 45m in/15m out rule for kids) and she's adamant it was much smoother than ours. Kids are wearing swim shoes (under protest) when swimming.

In the pictures below you can see areas that are more flat/dark grey, those are pretty smooth to the touch. I'm fairly sure the raised whiteish bumps are the problem, I can flake them off with decent fingernail pressure or a pumice stone. I have not yet engaged the company who did the plaster (yelp reviews mention an owner quick to yell and point out things that are not his problem), I'll probably give them a call in the next week or two to see if they can come take a look.

Anyone have thoughts on possible issue(s) or how to solve them?

 

[ajw22]

Welcome to TFP.

It sounds like the prior owners did not properly manage the pH during the plaster startup and you have scale on the plaster surfaces.

You have three ways of handling scale:

• Run your water chemistry at a low CSI of around -0.6 or even a bit below and it may melt the scale off over a few months. This is the least damaging to your plaster finish but will take the longest.
• Drain the pool and sand the plaster using diamond sanding pads with power sanders. Draining may not be advisable right now with you in California.
• Do an acid wash of the pool that will remove the scale but also etch the plaster, remove a layer of it, and weaken the plaster.

Turn on track CSI in PoolMath and enter your water temperature to see what your current CSI is.

Calcium Saturation Index (CSI)

How is CSI calculated? Very simple – use our PoolMath tool. To ensure long plaster life and save money, click here to learn more.

www.troublefreepool.com

@onBalance any advice on handling this scaling on 4 month old palster?

 

[hlarsen]

Thanks, I'll take a closer look at SCI and that link. After grabbing some goggles and taking a closer look it's mostly just on the sides, the bottom feels a lot less rough... of course I'm sure at least part of that is my older hands. The kids are definitely pushing off the sides where it's more rough and in general being less careful, so I'm sure that's a good deal of the issue.

 

[ajw22]

If you can reach the areas you can hand sand it using 80/100 grit wet/dry sandpaper.

 

[tommelton]

They also sell sponge sanding blocks, in various grits. Might be easier to use than regular sandpaper.

 

[ajw22]

Look for diamond 120 grit sanding blocks on amazon for $12.

 

[onBalance]

Allen, you have listed the best options to consider. It is scale.

 

[hlarsen]

Thanks for all the info everyone, I'll work on keeping CSI negative and pH down to help with this. I'd like to keep from draining the pool if at all possible and I don't want to damage the plaster, so with that in mind a few questions:

- It's safe to use the diamond blocks/pumice stone type abrasives without draining the pool? Can I just jump in and scrub?
- Any issues with the filter catching the scale or diamond block/pumice stone pieces?
- Any thoughts on a stainless steel brush vs the diamond blocks/pumice stone?

 

[ajw22]

It's safe to use the diamond blocks/pumice stone type abrasives without draining the pool? Can I just jump in and scrub?

Yes. You can sand the plaster while it is under water. Your filter or pool cleaner will pickup the dust created.

- Any issues with the filter catching the scale or diamond block/pumice stone pieces?

No, it is just calcium. You may see your CH level rise and some of it dissolve in the water.

- Any thoughts on a stainless steel brush vs the diamond blocks/pumice stone?

SS brush is not abrasive enough and will do more to roughen the plaster versus smoothing it.