Stains in Fiberglass pool

[Arizonaoldman]

I too have a 21,000 gallon fiberglass pool and a salt to chlorine generator. We have extreamly hard water and I just had my generating cell replaced after only two years. (free of course) Last year I began to have brownish 'build-up" at, or above the water line only in two areas (both wind driven areas) I had been using a 'Bio Guard" product "Off the Wall" on a weekly basis until late last fall. This year the stains are quite noticeable and no amount of "Off the Wall" and/or elbow grease seems sufficient. Do you think the Ascorbic Acid trick will work for me? Remember that most of the stain is above the water line. Will scrubbing with the ascorbic acid do the trick.

By the way I life in north western Arizona.

Ralph

[mbar]

If the stain is above the water line, then I don't know how it would be from iron falling out of the water. You can tell if it is mineral by rubbing a vitamin c tablet on the stain. If it takes it off, then ascorbic acid would work. You wouldn't have to scrub with ascorbic acid - just letting it touch the stain will make it disappear. Let me know if the vitamin C tablet (you can put a couple in a sock, soak the sock and rub it on the stain) works. If it is stain from leaves, they come off after chlorine is on them for a while. I have also had good luck with cleaning the water line with magic erasers. Hope this helps

[Arizonaoldman]

I tried the Vitamin C Tablet today. Got it wet then used it directly on the stain.
No luck whatsoever. Tried Mr. Clean Magic Eraser yesterday, still no luck. I refuse to give up.

Ralph

[mbar]

I read somewhere that you can put a little ph reducer in a sock, wet it, and rub it on the stain - if it is mineral it should take the stain off. You probably would want to wear gloves when doing this. Let me know if this helps. I wouldn't give up either!

[DavidD]

You are in good hands Ralph. Marie (mbar) helped me allot a couple of years ago and turned me on to the Vitamin C. I owe her much gratitude. I too have a Fiberglass pool and seam to have to treat my pool a couple of times each season. On another thread, waterbear has brought to light a yet unsubstantiated claim by a company (Water Tech I believe?) that a lack of calcium could cause problems in vinyl/fiberglass pools. No one is sure if this is true yet and I personally have my doubts but just for the sake of "research", would you post your numbers? Mine are as follows:

FC 3
CC 0
TC 0
PH 7.5
ALK 80
CH 60
CYA <30
Temp 84
16,000 gallon I/G Fiberglass

I currently have stains. My stains generally appear as grey lines running from one side of the pool to the other. They even appear as orange/yellow sometimes in certain light. The pool has been open for a couple of weeks now and the stains have progressively gotten worse. The last treatment was in August '05 and I'll be giving it the ascorbic treatment after the weekend. I'm trying to keep a log to try to figure out what is causing these stains and would like to compare others numbers when staining has occurred. I use a water filter (cheap RV type) when filling and have had my water tested for metals and there are no traces of Iron or Copper. Notice My Alk and CH are low? I'll be working on those after the treatment next week. I usually keep ALK between 90 & 100 and have never worried about CH but it has never been this low. I did do a partial drain when opening to get the CYA down and I guess the filter is working since no calcium seems to be added. Thanks in advance for your help.

Dave

[mbar]

Hi Dave, I am still trying to figure out what causes the stains. Your numbers seem perfect to me. Have you added any sequestering agent since opening? I also read somewhere that "Fiberglass has a negative electrical charge and can attract positively charged metallic ions, causing the development of a stain. The periodic addition of a metal treatment should help negate this effect and help keep pool stain free. " I don't know if any of this is true - but it would seem to be a reason that the fiberglass stains so easily. I haven't opened my pool yet this year, probably in about 3 weeks. I plan to add sequasol first before anything, then test all the chems and bring up the chlorine slowly. I think the most important is to have the sequestering agent in the water in a large quantity before doing anything at all, including a stain treatment. Maybe between all of us we can figure out why we get the stains - we know how to get rid of them, but it would be nice to not ever get them!

[waterbear]

I also read somewhere that "Fiberglass has a negative electrical charge and can attract positively charged metallic ions, causing the development of a stain. The periodic addition of a metal treatment should help negate this effect and help keep pool stain free. " I don't know if any of this is true - but it would seem to be a reason that the fiberglass stains so easily.

Can you substantiate this in any way? I would be interested in knowing where this statement came from.

[DavidD]

Marie,
I have not added a sequestering agent yet but had planned to after I did the ascorbic acid treatment. I would usually then backwash/replace DE and add more sequestering agent after all is said and done. Maybe I'll try just the sequestering agent first and see what happens. I'll let you know.
Now let me clarify, these stains are not that noticeable in full sun but usually in low light, such as evening, and I notice them more than others (maybe OCD?).
One observation I have made so far is that the stains appear to be occurring where the gel coat was sprayed in intervals. This is the only explanation for the almost perfectly straight lines that divide my pool in to 3 equal parts. I know that when gel coat is sprayed, you can usually only spray up to about a gallon or so at a time due to "kick off " times (the time in which the gel coat will start to cure). So it appears that where one part overlapped the other, staining is more prone. Makes we wonder if maybe there are slight indentions or something in these areas that collect the stains. After all, fiberglass/gel coat/resin is not absorbent so the stains occur at these locations for some reason.
Either way, It really isn't that big of a deal and if I had to do it all over, I'd still choose the same pool, stains and all!