CSI in winter (Fiberglass)

[Karl103]

I think I know the answer to this question but....

I leave my pool open during the winter and keep my chemicals balanced weekly.

I have a fiberglass shell inground pool.

It is very difficult to keep the CSI greater than -0.5 in the winter due to low water temps. Any concern about this for a fiberglass pool. Here are my latest numbers:

FC 5.0
ph 7.6
TA 80
CH 230
CYA 60

Thanks

 

[Texas Splash]

No real concern since our FG pools don't have calcium in them to worry about (etching). But if you ever want the CSI to me more neutral in the cold water, simply let the pH rise a bit more to 7.8-7.9 and that will help to balance it out more.

 

[C.Johnson]

I let the pH rise to 7.8 in the winter. Or raise the TA. Depending on how much rain you get, you can also raise the CH to 300-350 if the spring rains will flush it out. I generally have to add Calcium Chloride to most of my pools in the spring and fall here in Tulsa to get them back up to spec.

Water that is too aggressive will pull calcium out of the gelcoat on fiberglass pools and cause it to develop a chalky residue. Just took on a relatively new FB pool that clouded up whenever anyone swims in it. Rubbing against the wall leaves white residue on your hands. Increasing CSI to +.2 and brushing for a few weeks has resolved the issue.

This is the reason, I believe, TFP recommends maintaining adequate CH levels even with Fiberglass pools:
ABCs of Pool Water Chemistry

 

[Karl103]

Thanks so much for these answers - I decided to raise the ph slightly using Borax (since TA was already in range). I also added calcium to try to get it up to 250 but maybe will shoot for a bit higher.

Interesting issue with chalky residue on the gelcoat. I've had a whitish stain on the gelcoat over the last year. No real residue but the gelcoat looks "stained" - its only 3 years old. They look like streaks from the automatic vacuum moving over the area.

Do you think I should try to run the calcium up a bit (typically mine is 230-250 as recommended by TFP) or the Ph up a bit to get the CSI up and try brushing more ?

 

[Texas Splash]

Interesting issue with chalky residue on the gelcoat.

Karl, I saw CJ's post as well. There are other members who experienced the same issue where the white residue "wiped off" somewhat easily which is different than some pools (like mine) with a faded chalkiness that did not wipe off. For those shells with the chalkiness that wiped-off by hand, the increased CH, TA, and or pH seemed to resolve the issue. For the others (like mine), it did not. See My Story Here. Seems to be different chemical/product/gelcoat issues as the chalkiness was definitely embedded and not something on the surface that could be wiped so easily. Some manufactures will claim it's an oxidation reaction from pool chemical maintenance, but that's an argument hard to prove or disclaim since some pool owners are very meticulous about their levels, while others not so much.

The reason TFP has always advocated a minimum CH was solely to prevent staining (i.e. colbalt, but others as well). It has been TFP's understanding based on replies from Lathum, San Juan, Viking, etc that calcium is no longer used in the manufacturing process of today's FG pools, therefore the CSI rule "shouldn't" really apply. But there does seem to be scenarios where chemicals allowed to stray too far outside the recommended ranges begin to impact the gelcoat, but we don't know exactly why. In some cases, we also believe defective gelcoat applications are also a possibility, in which case chemical level adjustments would have no bearing.

In short, I would refer to the TFP recommended levels and try to stay within those parameters. That's your safest bet to ensure the water is balanced properly, not only for algae prevention, but also to ensure the water is not too hard (scale) or aggressive.

 

[Karl103]

Thanks for your reply Texas Splash. I read your story before because I think I am having the same problem with my gel coat. I can tell you I am very meticulous with testing and keeping CSI in -0.5 to -0.3 when water temp is warmer in Spring/summer.

my questions:

Do you think the staining represents any long term damage to gel coat? Other than my obsessiveness, the rest of my family could care less and they think I am crazy.
Could the staining represent simple sun caused fading of the color ? Maybe we are just worried too much about mild aesthetics ?

Do you think I’ll have any luck if I reach out to manufacturer ?

 

[Texas Splash]

You are asking the same questions I did when I noticed ours changing. The inner OCD in me came out big time. Simply put - I don't know. It doesn't rub-off, and as you know from my previous thread, I even physically removed the chalky appearance to see what happens. I've been very careful to not let my water get too aggressive worrying about scale, and instead try to keep the CSI more neutral or even slightly positive as I have no SWG cells to worry about. Most of my sanded areas still look darker than the parts I never sanded. But the jury's still out. I'm watching to see if it's simply a natural gelcoat oxidation process (like naturally above the waterline), or if the more aggressive water of the past was a contributor. I can just about guess what the manufacture will tell you. First question will be do you have proof of water testing from a pool store (since purchase) to see if "their" recommended level were maintained. Makes no difference how incompetent store testing and summer hires can be, without that they will say the warranty is void. Then they may provide a regurgitated a reply that has been provided to many owners who claim to have the same faded appearance. A couple of us received the exact same (template) reply claiming poor water testing, pH oxidation, etc as the cause.

If your chalkiness is not the kind that easily wipes-off (like mine), it will probably remain there unless you physically have it sanded/buffed out. As you may have noticed, the appearance varies upon the angle of the sun, so sometimes it's more noticeable than others. Like you, I think the only person who really cares is me as I'm the primary caretaker of the pool. Everyone else just jumps in and doesn't seem to notice it unless I point it out. For now, I just keep my water balanced close to neutral and not let it bug me too bad. The pool is till beautiful to look at, and in the summer everyone enjoys it for the relief and fun it provides. You can toy-around with it if you like over time, but I wouldn't let it get you down too much. Enjoy your investment.