Fiberglass Pool Calcium Buildup or Fading Gel-coat?

[rbabin]

I installed a fiberglass pool 2 years ago and noticed all the flat rough surfaces appeared to be fading. I was then told by the pool installer that it was a calcium buildup and it could be scrubbed off. I have tried numerous scale removing solutions including Jacks Magic but it hasn't budged. I was able to drain the pool to below the first step. Once the step dried it was almost completely white but all the walls were still a nice dark blue. I tried putting muratic acid on a small section of the step to see if it would come off but no luck. The white film is smooth to the touch. Any advice?

I have a 36'x16' Lexington fiberglass pool with a 10' hot tub with spillover. I'm using a copper system and only had to use muratic acid to adjust the pH and Clorox as a sanitizer once a week. The pool has always been crystal clear since installed.

Thanks,
Randy Babin

[PoolDoc]

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[PoolDoc]

I installed a fiberglass pool 2 years ago and noticed all the flat rough surfaces appeared to be fading. I was then told by the pool installer that it was a calcium buildup and it could be scrubbed off.

Are you familiar with the acronym, "CYA", as in Cover Your A##? It looks to me like that's what the installer is doing, here.

Quick test: get some muriatic acid or sodium bisulfate (pH Down). Mix up a cup of 1/3 acid + 2/3 water. Pour it on the step.

If it fizzes, it's calcium carbonate. Rinse it off after 5 minutes. If there's no change, and no fizzing, take good photos, and check your pool warranty details.

Good luck!

[rbabin]

Thanks and I appreciate the help. Prior to your reply I did pour a small amount of straight muratic acid on the step and nothing happened. You think it could be calcium phosphate? I had the water tested today and they said it was perfect. I even checked for salt and phosphate content. I've been in touch with the manufacturer and waiting on their reply. I have old photos taken and it developed in 7 months, between March to October. I would hate to sand it down and ruin the gel coat. Have you ever heard of some sort of sand blasting to get it all out from the rough surface then applying a new gel coat?

Randy

[PoolDoc]

I can't immediately rule it out, but . . .

1. Gel coat oxidation is common and well-known;
2. Calcium phosphate pool scale is rare, with only one confirmed case on Google.
3. Phosphate remover companies have latched onto possible phosphate scale as a NEW reason to sell removers.
4. Insoluble phosphate chemistry is nastily complex, with limited empirical data on when scale forms in boilers

I dug around a bit, and found some data, but it will take me quite a bit of time to wade through what I've found. I'm not willing to do so, unless you are first willing to do your part:

1. Take a series of photos of the areas with discoloration, gradually zooming in on a fixed area, till you have reached the maximum macro capability of your camera. Take the pictures in the early AM or late PM so there the texture of any scale will be revealed by shadowing. Email them to me (poolforum@gmail.com) FULL size.

2. Purchase a Taylor Technologies Inc K-1106 Phospate Test Kit
. Test BOTH your fill water AND your pool water. If levels are high, you'll need to dilute in order to get meaningful results. Use distilled water from Walmart: www.walmart.com/ip/10315382

3. List ALL the chemicals you used this season and last, with special attention to stain / scale remover products and any products made by United Chemical. Also if you've used any pH control products that claimed to be 'buffered' or especially long lasting, it's critical that you ID and list those. In the past, some various phosphoric acid compositions have been sold in that manner. As accurately as you can, list quantities.

Best wishes,