Help! Crystals Growing On New Plaster

[poolnotrite]

I hope that someone can help me with this problem. We renovated an inground pool 2 yrs ago and switched over to a SWG. We live in the northeast and pool is 24,000 gal w/plaster finish. After 1st season upon opening pool we found that there were very sharp crystal like deposits on the plaster making it feel like 20 or 30 grit sanpaper. They would cut you if you scraped against them. They are very tough to remove and are all over the entire surface of the plaster. We closed with a regular closing kit for the first season.

This past season we tried an experiment when closing to see if the crystals would return. we emptied the attached hot tub and the person who replastered the pool ground down all the crystals with a diamond grinder to a very smooth finish. We treated the water in the main pool with a salt water pool closing kit and then pumped that water back into the hot tub. We took the cover off the hot tub 2 days ago and the problem had returned but with the added result of the crystals growing. Now there are glass like crystal growths as long as 3 and 4 inches!!!.

We are now thinking of a replaster but trying to exhaust all avenues of remediation before we do that.

I can't help but think that there is some chemical out there that may help this situation.

I do have some pics of the crystals if it would help. I can also supply water chemistry info at times of closing if anyone cares to tackle this topic.

[swimmer123]

I have the same problem.

I don't know if any of the following is relevent, but maybe we have some commonality here.

I live in the Toronto area. We have a salt water pool. We had problems with the finish of the marbelite, so the supplier drained the pool and tried to grind it smoother (they did not do a good job). Anyway, the pool was refilled with fresh water and closed for the winter. There was no salt added (vendor said it would not dissolve well since it was already so cold.. better to add salt again in Spring). So basically, it was put away with just fresh water.

4 months later, I take off the cover to discover these crystals. Many are loose on the bottom, but most are stuck to the walls and bottom. They are clear when removed from the pool, but appear to be white when they dry.

If it makes a difference, the vendor left the marbelite dry for at least a couple of weeks until they got around to refilling it. Coincidentally, there is now a crack at the bottom - related?

Have you discovered the cause of the crystals? Is this some kind of concrete chemistry going on? Is the marbelite leaching? Is the concrete shell doing something funky.

Thx

I hope that someone can help me with this problem. We renovated an inground pool 2 yrs ago and switched over to a SWG. We live in the northeast and pool is 24,000 gal w/plaster finish. After 1st season upon opening pool we found that there were very sharp crystal like deposits on the plaster making it feel like 20 or 30 grit sanpaper. They would cut you if you scraped against them. They are very tough to remove and are all over the entire surface of the plaster. We closed with a regular closing kit for the first season.

This past season we tried an experiment when closing to see if the crystals would return. we emptied the attached hot tub and the person who replastered the pool ground down all the crystals with a diamond grinder to a very smooth finish. We treated the water in the main pool with a salt water pool closing kit and then pumped that water back into the hot tub. We took the cover off the hot tub 2 days ago and the problem had returned but with the added result of the crystals growing. Now there are glass like crystal growths as long as 3 and 4 inches!!!.

We are now thinking of a replaster but trying to exhaust all avenues of remediation before we do that.

I can't help but think that there is some chemical out there that may help this situation.

I do have some pics of the crystals if it would help. I can also supply water chemistry info at times of closing if anyone cares to tackle this topic.

[chem geek]

I can also supply water chemistry info at times of closing if anyone cares to tackle this topic.

This doesn't sound like scale which would by white and not clear, but if you post your numbers on closing then that might help. In an SWG pool, there is a strong tendency for the pH to rise (due to the aeration from the hydrogen gas bubbles produced in the SWG) so if the SWG were kept running and there wasn't any acid being added to the pool to lower the pH, then a high pH would lead to scaling which is the precipitation of calcium carbonate. Was the SWG running over the winter after the pool was covered?

The specific numbers that are needed are pH, Total Alkalinity (TA), Calcium Hardness (CH) and Cyanuric Acid (CYA). I assume with the SWG that the salt level is around 3000 ppm, but if you know differently then you can post that as well. If you know the temperature, that's also helpful.

[poolnotrite]

I can also supply water chemistry info at times of closing if anyone cares to tackle this topic.

This doesn't sound like scale which would by white and not clear, but if you post your numbers on closing then that might help.  In an SWG pool, there is a strong tendency for the pH to rise (due to the aeration from the hydrogen gas bubbles produced in the SWG) so if the SWG were kept running and there wasn't any acid being added to the pool to lower the pH, then a high pH would lead to scaling which is the precipitation of calcium carbonate.  Was the SWG running over the winter after the pool was covered?The specific numbers that are needed are pH, Total Alkalinity (TA), Calcium Hardness (CH) and Cyanuric Acid (CYA).  I assume with the SWG that the salt level is around 3000 ppm, but if you know differently then you can post that as well.  If you know the temperature, that's also helpful.

Chem Geek,

Thanks for the post. Sorry for not getting back right away. I had some password difficulty with the site. I will post my closing numbers as soon as I can.

For now the SWG was not running over the winter. and the pool was covered.

[chem geek]

Sometimes calcium carbonate (calcite) can look clear, not just white. Did the crystals look anything like those in these photos? Usually scale forms as a rough surface that builds up, but perhaps in still water it can form as crystals.