Fiberglass pool - fading under waterline after 1/2 years. Heater and SWG. A story.

[MoogMan]

Strap in!

2 year old fiberglass pool. Major fading below water level. Pool shell manufacturer Alaglas came out 6 months ago, tech sanded a small piece of step and said its calcium. Advised me to lower calcium to 0
If possible(?) - my hardness was already low (90ppm) so I found this all suspect. I have since read that in a fiberglass pool calcium should be at 200 or so plus (like pool math suggests) to act as a buffer.

I am an a little bit obsessive and avid pool tester, and have used nothing but Taylor kits and TBP pool math recommended levels since day one.

Anyway. The pool tech recommended I buy some jacks magic blue remover - it doesn’t work. Firstly it has to be sprayed on and brushed, I cannot comeptlelu drain my pool for obvious reasons. I did however drop it over half and try the remover but to no avail.

The only joy I’ve had is with sanding a test area - I actually used an 80 grit as that’s the only way I saw any results. Event this only removed a small amount in certain areas. The stain is not scaled or flaky, it does not come off with any physical manipulation except sanding which makes me think it it has been ‘baked’ into the shell. Even then I think the majority of it is oxidation or chlorine bleaching.

I have pool math water balance receipts going back to day 1 shaking my water chemistry as always been within the correct levels. I don’t even use cal hypo shock.

After extensive researching of the subject and trying to find others in a similar boat (there are many) I stumbled across this post on the Australian home one forum:

“Below the water indicates it is a water problem . Prolonged high chlorine or ph. Generally it is pools with a heater on the same pump as chlorinator or people using a pool blanket . Even not turning the chlorine output down in winter can cause high chlorine over winter. All the pools I have seen like this have had heaters connected through the filtration circuit with a salt chlorinator and a solar blanket . This combination will have massive spikes in the chlorine level whilst heating .”

I have a heater with my salt cell in line with it (after the heater, before the return). I have no solar blanket. It’s interesting he says how most of the pools he’s seen with this issue have Themis combination. I personally haven’t seen any spikes (I test every 2 days, sometimes daily) when heating the pool. I don’t understand how this would be a problem but any input and advice would be greatly appreciated. Hoping @Texas Splash sees this as his posts on the matter have been so enlightening.


(On a side note, I noticed some brown staining in the pool at did the vit C test - raised up immediately so I believe it’s iron. Will an absorbic acid treatment be okay if I don’t have a heater bypass?)

 

[HermanTX]

Bumping this for more visibility. @mgtfp or @1poolman1 @mknauss

 

[Texas Splash]

I'm afraid it's not calcium. Yes, some owners neglect their chemistry and it can be accelerated by covers and equipment. But I suspect your shell, like mine and so many others, is experiencing a transition that is not from anything you have done wrong. Some gelcoats simply fade quicker or beyond the normal transition one night expect, and there seems to be no explanation. Try not to let it get the best of you. It's tough, but enjoy your pool for what it is.

 

[mknauss]

(On a side note, I noticed some brown staining in the pool at did the vit C test - raised up immediately so I believe it’s iron. Will an absorbic acid treatment be okay if I don’t have a heater bypass?)

Do not run the pump when you do the AA treatment. Just pour in the AA and brush it around. It will immediately life the iron stains (if the FC was zero before adding the AA.) Add more AA if necessary.

You should then drain/exchange the water and refill with iron free water.

 

[Homebrewale]

I'm afraid it's not calcium. Yes, some owners neglect their chemistry and it can be accelerated by covers and equipment. But I suspect your shell, like mine and so many others, is experiencing a transition that is not from anything you have done wrong. Some gelcoats simply fade quicker or beyond the normal transition one night expect, and there seems to be no explanation. Try not to let it get the best of you. It's tough, but enjoy your pool for what it is.

After reading your story and several others, I've come to accept the faded fiberglass. Unless someone comes up with a permanent solution, I'm not going to take the time to sand and then have it fade again within a year.

 

[1poolman1]

After reading your story and several others, I've come to accept the faded fiberglass. Unless someone comes up with a permanent solution, I'm not going to take the time to sand and then have it fade again within a year.

All you are doing by sanding is removing a bit of the gel coat that makes up the surface of the fiberglass, especially with 80 grit. That's very aggressive.
I've seen that condition in virtually every fiberglass pool with walls like that, uniform color and no tile. Even the fiberglass pools with a multi-color surface get lighter at the top. Sun? Chemicals? Sun and chemicals?

 

[Homebrewale]

All you are doing by sanding is removing a bit of the gel coat that makes up the surface of the fiberglass, especially with 80 grit. That's very aggressive.
I've seen that condition in virtually every fiberglass pool with walls like that, uniform color and no tile. Even the fiberglass pools with a multi-color surface get lighter at the top. Sun? Chemicals? Sun and chemicals?

I'm not the OP who was sanding a spot. The fading in my fiberglass pool is from waterline down. So I would guess it is not the sun causing it.

 

[MoogMan]

Mine is fading from water level down. Above water level is perfect.

 

[JoyfulNoise]

The gel coat is undergoing hydrolysis which breaks down the polyester resin and causes the surface to become microporous. This leads to reflection difference in the way light hits the surfaces which appears as haze or white scale. Over time the hydrolysis gets more severe and the gel coat begins to physically deteriorate which will be seen as chalkiness that you can rub off with your hand. The sanding simply removes the affected layer. There’s not much you can do about it as it is the natural consequence of submerging a polymer surface in water. Boats undergo a similar phenomenon but they are easier to repair and the gel coat is usually covers with a hardened wax layer to make it less susceptible to water damage.