Fiberglass salt water with possible scale & color changes

kjfrazi

Member
Oct 9, 2023
9
South Central PA
Hi,
This is our 4th year of our 16x40 Barrier Reef Fiberglass pool. We are in Pennsylvania south of York so our open season runs from mid-April to late Oct. We use a heat pump heater on the beginning / end of season.

Generally speaking we have had no issues at all the past three seasons but this year we are seeing two issues we don’t understand.

First the numbers taken with a Taylor Salt water (K-2006) test kit and logged into pool math.

Free Chlorine: 2.6
pH: 7.4
Total Alkalinity: 120
Calcium Hardness: 180
CYA: 30 (low we will increase)
Salt: 2930
Temperature: 87°F

Water is very clear with no issues with that. We run the DE filter 7am to 10pm so its getting 15hrs a day of circulation.

FIRST ISSUE - We noticed the gel “non-slip” areas on the steps is turning whiter than the rest of the pool (attached photo)

So we went to the pool store where we purchased this pool from and they said that the gel-coat needs calcium, as the water is taking it out of the fiberglass. Research on your site suggests that this could be true.

We were told to add 18lbs of calcium chloride. According to the pool math, I should add 50 more lbs. to get to a 450 level ? Seems like a large amount to add after adding 18lbs.

We also added 10lbs of baking soda to increase the alkalinity after the pool store said it was 88 and they did not like it, so added more. Now may be too high ?

SECOND ISSUE - We are seeing some sort of scale (Is it scale?) on the vertical surfaces. (attached photo) It does not seem to be on the bottom so could be a similar gel coat issue.

I am concerned that adding all this calcium & baking soda will increase this scaling. I tried brushing this off the walls and it does not come off. We run a Dolphin pool cleaner 2 hrs. a day and the walls are covered by cleaning so it’s not being removed.

The pool place again said that this could be because the calcium is being extracted from the fiberglass.

They sent us home with ½ gallon of SC-1000 Scale and metal Control but trying to learn more of possible causes and ways to fix before I use this.

Any ideas on this would be greatly appreciated.

Ken
 

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Ken, welcome to TFP! :wave: I hate to be the bearer of bad news, but I don't think it's scale. Unless you have a heater or waterline tile, you really don't need calcium except for perhaps a very small amount simply to help prevent staining. At TFP we list a CH minimum of 250 just to help cover all scenarios, but you literally could have a CH of 50-100 and be fine. Increasing the TA won't change the chalky look and will only frustrate you with the pH rising faster, so you'll play the yo-yo game with acid up & down.

IMO, what I see happening is the same thing that happened to our shell at about year 3 or so. It doesn't happen to all FG shells, and to-date there is no rhyme or reason as to why some change like that so fast while others do not. I would encourage you to review my own experience listed below before you waste anymore money with gimmick products. I doubt they will help anything but the seller $$$.

 
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