UnknownStain - Fiberglass Pool

[Skillset]

Hi All,

My pool has been covered for about 2 weeks (solar cover) because weather and temp. has not been ideal swimming weather. I have been testing the water every-other-day, though, and keeping up with the water. Today, I rolled off the cover and noticed 5 stains at the bottom. Each stain is round and very large - ranging from 4"-6". 3 are in the shallow end and 2 are in the deep end. I have a 16x33 IG fiberglass pool that was installed this June - 13,500G. Fiberglass is light blue. The stain appears as light brown - it's almost like a grease stain bleeding through! If it's sunny out, you can't really see it, but if it's cloudy, you can see it pretty well if you look for them.

Since installation, I've been using Cl pucks. I'm aware of the CYA issue - but current levels are okay, so I haven't switched yet to bleach. Only during the past 2 weeks, the Ph levels dropped a bit, so I added some pool-store PH+ (bought the Soda Ash before I knew Borax would be ok). Did this about 4 times this past week - adding about 12 oz each time. Right after installation, I did put CYA in. And, I did shock once in early July using cal-hypo. Have not shocked since. Water has been crystal clear and have had no water issues.


A recent test done today:

Cl: 6 (Consistent between 3-6 all summer)
FC: 6 (Never ever test positive for CC)
CYA: 50
Alk: 90 (conistent over the summer)
Ph: 7.3 (since installation, was very stable at 7.5. Since covering 2 weeks ago during non-swim times, pool seems in need of PH+ sometimes.)

I'm probably going to call the fiberglass manufacturer on Monday, but thought I'd post this to see if any fiberglass owners ever experienced this issue. Seems like the fiberglass somehow got stained. And, the only thing differently done in the last 2 weeks was the add of Soda Ash and covering the pool when not in use.


I would have posted a picture, but the camera is not picking up the stain. I am running a heat pump, too and keeping the pool at 86.

[mbar]

It may be a metal stain. If you have any ph down, or some vitamin C tablets, you can try it on the stain. Crush the vitamin C tablets up and rub it onto the stain. IF the stain goes away, it is a metal stain. You can also try some ph down in a sock and rub it on the stain. Your fiberglass pool will stain from metals very easily. Adding the soda ash could have reacted with the chlorine in the water and dropped some metals out of solution. If it is a metal stain, you will need to get some metal sequesterer, lower the ph down to 7.2 and add at least as much as it says on the bottle, more is better than not enough. IF the stain is not removed after a few days, then you can do a stain treatment. Let me know how you do, and feel free to ask any questions you may have.

[Skillset]

Hi Marie,

Thanks for your reply! Here's a dumb question, if the stain is at the bottom, how do you rub the crushed-up Vitamin C on it? Is there a technique to get the liquid onto the stain?

Same questions with the Ph-? Is there a technique for applying to the bottom of the pool?

The stain in the least shallow part of the water is at about 4' deep.

Is one test easier to perform under water than the other?

Thanks again!
Marc

[mbar]

You can tie the sock onto the skimmer pole and let it sit on the stain. You can put a couple of crushed vitamin C tablets in a thin sock or pantyhose, and tie it on the skimmer pole and let it sit on the stain. If you want to see if the stain is organic, then you can crush a trichlor puck up and do the same. If the stain is llifted by the chlorine tablet, then the stain is organic, and will lighten with high levels of chlorine. If the stain is from metals, then you will need the sequesterer or a stain treatment. Sometimes if the metal stain is new, you can lift it off with just the sequesterer. In my opinion it is a metal stain, because it fits with everything you have posted - and you have a fiberglass pool. You can read back through the metals forum and see that it is very common, and can be taken care of Let me know how the tests go, and I can help you further.

[Skillset]

A thousand thanks, Marie. I'll try to do the test today, but I need to do it when it's not sunny and, as you know, it's a beautiful day here in the tri-state area. So may have to wait a bit. Pool closes in 2 weeks, so I need to get it done! Hard to believe the the "gel" from a Vitamin C tab will remain in a sock, but I'll give it a try!

Do you have a San Juan pool ? I was wondering because the 16x33 is sort of uncommon (at least the 33 is) and we both have the same size. Mine's an Atlantic.

Anyone, I've been reading the manufacturer site and it says don't use a sequester (not even sure what that is). They recommend Jack's or Metal Magic. See: http://www.sanjuanpools.com/maintenance.html

Reading about Jack's, it says it's "heavier" than water, so I guess it floats down to the stain.

In any event, looks like it's treatable, which is great news.

Again, thanks!

[CallMeIshmael]

Hey Skill,
Just FYI, Marie (and WaterBear & ChemGeek & more- Thanks to you all!) have posted excellent details on those products, how they work, their compatibility with fiberglass, and the whole chelating/sequestering issue. You'll find tons of info by searching for Fiberglass Stains or those product names. I would post a link, but there are easily a dozen threads I've found invaluable. Best of luck tackling this before closing!

[mbar]

Sorry, but I never saw a vitamin c gel tablet. I have only had the solid form, so I don't know how you would get the gel on the stain without going in and rubbing it on by hand. Yes, it is a beautiful day, and I was just out getting the pool ready for closing I hate closing - it means it's the end of the summer. Anyway, I would just get the sequesterer for now, or not even do anything - I have closed with stains, and opened stain free. I think it may be that the the ph gets low over the winter, and as the chlorine gets low, the stains lift off. So in my experience, I wouldn't worry much about it, because you don't need to put any extra money in at the end of the season, and the stain treatments make it hard to rebalance the water - so if you want to close in the next two weeks, I wouldn't worry about the stain for now. If it is bothering you, you can do the sequesterer - I would recommend metal magic, because it is supposed to turn any metals in the water to salts, so they can be filtered out. Jack's magic is a very good product also, but it just sequesters the metals, unless you use the stain treatment which is ascorbic acid, and that will take a while to rebalance after the treatment. You also can't shock the pool for 2 weeks after the treatment, so you won't be able to close right away. Let me know if you have any other questions.

[Skillset]

I'm taking your advice - will probably treat next year. Again, thanks for your help.

[Skillset]

Pool company has stood me up the last 2 weeks, so the pool is still uncovered. So, I took the above advice. Crushed up 8 Vitamin C tablets in a pantyhose, attached it to my skimmer pole with duct tape, and rubbed the pantyhose on the stains. No more stains ! Also, tried the Vitamin C in my stainless steel sink and it removed some of the iron stains there too.

Thanks for the great advice!

[mbar]

Just wanted to add to the thread, one of the reasons that you probably got the stains in the first place is that when you added the ph+ your chlorine may have been high. High ph + high chlorine will make any metal that is in the water fall out onto the pool surface. I don't know why your pool manufacturer would not endorse a sequesterer, but will endorse metal magic or Jack's Magic - the Jack's Magic pink stuff is a sequesterer! In any case, check your trichlor tabs to see if they have copper in them - some of the trichlor is adding copper as an agelcide right into the tablets. Fiberglass pools are very suseptable to staining. I run my pool at a ph of no higher than 7.4, and keep the chlorine at the low end of the "best guess" chart. I also keep a sequesterer in the water at all times. One way to handle stains that pop out is to take the ph down to 7.0 - 7.2 and add a sequesterer - this will sometimes lift a stain that is new. If the stain gets more embedded, then a treatment with ascorbic acid (vitamin c) will take them off. I hope you got your pool closed for the winter, and next year when you open I can help you keep your pool stain free I can't waint till the next swim season