Scale or Calcium buildup??

[Tjk1812]

Good evening to all...I’m new to the forum and hope some people give me some info.

First, I have a fiberglass (32x16) and it just had its 4th season. I noticed last year, and especially this year a white substance beginning to buildup on the steps, walls and floor. I’m pretty picky on keeping the water chemistry in check so never thought too much about it.

This past weekend I winterized the pool and drained some water to expose the steps and wow, was it white! I took a water sample to be tested and the results...TH-250, TC-3, FC-2, pH-7.1, TA-60, CyAcid-10. The water chemistry didnt seem too bad but I did raise my TA. I have city water (Del Co) and the pool was originally filled with it, and I use it to top off as I have an automated cover so it never gets filled with rain. I did a saturation index check last year and I was at -3.

I ran my fingernail over it and it will not come off. I know gel coat is permeable to water and my thinking is the dissolved minerals in the water have come out of solution and deposited under the gel coat. Del Co water has a history of being high in minerals and I think this is what I’m seeing...I hope??

Im thinking of trying Scale Tec Plus next year, maybe every 2 weeks and see if it changes. Has anyone seen or had this problem, and if so were you able to correct the problem? Any info would be greatly appreciated.

Tom

 

[mknauss]

I have a fiberglass pool and it looks the same when I drain it. Once filled up I do not see it.

Not sure it is worth be concerned about. But willing to learn.

Your test results look like they are from a pool store. No way you can get a CYA of 10. We would suggest you get your own test kit and not use pool store testing. It is notoriously incorrect and not repeatable.

I use the TF100 from TFTestkits.net. Check it out. Would be a good purchase over winter to take care of your pool next year.

Take care.

 

[Tjk1812]

Thanks for response...yes, the results were from my local pool store. I’m going to get pool kit this winter, others have said to do the same.

Im just concerned because it’s getting worse every year. I think it’s scale or calcium buildup and my city water is high in dissolved minerals. I’m going to try Scale Tec next year and if it works I’ll make it part of my routine maintenance.

 

[mknauss]

I am sure it is not scale. It could be other minerals. Our water is from the Colorado River so high in Calcium and TA.

Take care.

 

[pooldv]

I agree that it isnt scale and I doubt it is minerals either. I'm not sure but I've seen enough fiberglass pools with that same issue that I'm starting to form the opinion that it is just the gelcoat surface starting to breakdown. Fiberglass boats need to have the gelcoat surface redone periodically and/or use bottom paint because the gelcoat below the water level starts to fail over time.

I believe there is someone here who is trying some very fine grit sandpaper to clear it up. But, I habent seen a follow up on that recently.

 

[mknauss]

Our pool shell is three years old. And we actually drained it one year after first fill and it was already white. I do not think there is anything really damaging other than eventually, hopefully 10 years or more, it will need to have new gel coat. As I have said, it looks fine with water in it.

Thanks for the input ----

Take care.

 

[Drd]

That looks like the effects of long-term exposure to chlorine, try leaving something plastic in a bucket of chlorine water for some time and pull it and dry, see if that tells the story.

 

[Tjk1812]

My pool is a salt water pool and I check the chlorine pretty regularly..about 1-2 times a week and it was always in the 2-4 ppm range. The only time I can recall it being much higher was when I put the cell in a ‘boost’ mode due to many swimmers in at one time.

 

[mknauss]

My pool is a salt water pool and I check the chlorine pretty regularly..about 1-2 times a week and it was always in the 2-4 ppm range. The only time I can recall it being much higher was when I put the cell in a ‘boost’ mode due to many swimmers in at one time.

On the testing and chlorinating -- here is some reading --
Pool School - ABCs of Pool Water Chemistry
Pool School - What is TFPC?
Pool School - Chlorine / CYA Chart
Pool School - Water Balance for SWGs
Pool School - Test Kits Compared

Take care.

 

[Tjk1812]

I’ll check it out. Thanks for all the help, everyone on this forum has been great.

 

[Teald024]

I’ll check it out. Thanks for all the help, everyone on this forum has been great.

Hello neighbor and Welcome to TFP! you will be glad you found your way here! I live about 20 minutes north of you.

In the Spring, you can check if it is scale by putting a bit of diluted acid on it and see if it bubbles. I thought DelCo softened their water prior to distribution(?) Unfortunately their water report doesn't list hardness. It isn't an EPA regulated component. When you get your test kit, you can test the water for yourself. We have very hard water up here. No discount for pool fill, bummer.

I'll repeat what you've heard and suggest a good test kit. any money spent on it will be easily saved in reduced chemical use and other problems

 

[YippeeSkippy]

I have a deep blue fiberglass pool also, and see this along my water line too. Once the water is over the line you don't notice it, but drop your water level and you do. I do NOT think it is calcium as I live in an area with extremely soft water. My CH was very low for months before I knew you were supposed to test things other than just FC.

Having upped my CH, it never increased nor decreased the water line.

Maddie

 

[FnC80]

Being it’s fiberglass, I’d assume it’s just oxidation and UV exposure and not chemicals as others have stated. My fiberglass boat also gets that “chalky” look after a season of use and requires a thorough waxing to restore the shine though when wet you never notice it. If it really bothers you over the winter, wet sand it with 3000 grit and buffing compound to finish along with a coat of wax.


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17.7k gal, 98 ft perimeter, IG quartz, 3HP EcoStar VSP, 1.5HP TriStar Dual Speed, 725 sq ft SwimClear Cartridge, Rainbow chlorinator, Paramount clear O3, Pro Logic controller, 500k BTU heater, AquaVac 500, Spillover Spa, 3 sheer waterfalls, 3 bubblers.

 

[Tjk1812]

Teald024..I tried the acid test when I was closing the pool for winter and no bubbling. I don’t think it’s oxidation either because I have an automatic cover, so it’s primarily out of the sun most hours of the day. I’m going to try scale Tec next year at opening, take some before and after pics, wait a month and if it’s better make it part of my pool maintenance. Oh yeah, and get a better test kit. Thanks for all the advice!

 

[venno]

Teald024..I tried the acid test when I was closing the pool for winter and no bubbling. I don’t think it’s oxidation either because I have an automatic cover, so it’s primarily out of the sun most hours of the day. I’m going to try scale Tec next year at opening, take some before and after pics, wait a month and if it’s better make it part of my pool maintenance. Oh yeah, and get a better test kit. Thanks for all the advice!

I have a small fibreglass pool in Perth, Western Australia. Its been in for 5 years and started to develop this buildup after only 3 yrs and now everything below waterline is basically white, as I discovered when I had to drain pool for some maintenance.

NB. our local water is very high in calcium and lime.

I had the pool guys around and they stated it was calcium staining and recommended lowering pH to 3 for 24 hrs and then try scrubbing walls. This achieved nothing and the material would not move.

I then found an online stain remover company and they also, based on my pics, said it was calcium and sold me a 3 part chem kit to dissolve the material. This had no effect.

I then contacted the pool builder company and they said this was normal for Perth due to the water and it was nothing to worry about as it would not damage the gel coat. They stated that it was only a visual and feel (feels slightly rough) issue, but if concerned could try fine sandpaper to remove material and restore pool to as new look. They stated that it is not a stain and referred to it as plating and that no chemical or chem process would soften or remove it.

Could be rubbish but then so has everything the pool guys/experts told me so far.

 

[domct203]

That looks like the effects of long-term exposure to chlorine, try leaving something plastic in a bucket of chlorine water for some time and pull it and dry, see if that tells the story.

That was actually done by a member here with a piece of vinyl liner. As far as I recall, there was no noticeable change to the liner after months of exposure.