Yellow stains on fiberglass

[DOMO]

Hi all, Not sure if this is the right place to post this topic, but does anyone know why we are getting yellow stains on our white fiberglass pool? I've tried to brush it off, but that is not working. What is the cause and how do I remove these stains? Many thanks!

 

[BoDarville]

Our pool occasionally gets similar staining from some sort of plant/pollen that occasionally gets blown in on windy days. While it does not brush out immediately, it goes away on its own usually on that same day.

In your case, it could range anywhere from that to metal stains to (hopefully not) mustard algae. One quick way to determine if it is metal vs. organic in nature is to take a Vitamin C tablet and rub that on a part of the stain. If it goes away, then it's metal. If you do not have a Vitamin C tablet then you could approach it from the other angle...try rubbing a trichlor puck on the stain. If it fades, then the stain is organic and not metal.

Of course, posting a full set of test results will allow us to help you better by giving us a bit more insight as to what's going on.

 

[DOMO]

hi. thanks for the reply. we have had a LOT of pollen and things blowing in from the trees lately, but the stains are not rubbing off. a vitamin c tablet, like a supplement pill? (sorry, pool newbie here!). re: metals, we did just add a few inches of water from the garden hose to bring the level up, and we have hard water locally. had planned to use Pool Magnet Plus after adding that, as the local pool store recommended it whenever adding water from the garden hose. is it possible that could remove it (if it's from metals)? i am taking a water sample to the pool store later this week to run full diagnostics, so i can reply back with accurate numbers at that point.

 

[BoDarville]

a vitamin c tablet, like a supplement pill?

Yes, exactly. Vitamin C contains ascorbic acid and will remove metal stains. If the stains are indeed metal, you can purchase a larger quantity of ascorbic acid to remove the stains. Here's a bit more information on dealing with metal stains: Metals in the Water and Metal Stains

BTW, if the Vitamin C is in an enclosed capsule, you will have to break/crush the capsule so that the raw Vitamin C gets in direct contact with the stain.

 

[DOMO]

Hi again. Sorry for the delayed reply, we continue to suffer through our nightmare pool experience (story for another post!). We recently had to drain the pool for an inspector, which is why I'm so delayed in following up on this. When it was drained, we tried rubbing vitamin C on the yellow stains but with no luck. The pool was recently refilled and we had the water tested several days later (with good results) and the yellow staining continues to get worse. Not sure what #s you need from the test results, but here are a few:
CYA 11
TDS 400
PH 7.5
Tot alkalinity 116
Tot hardness 193
Mustard, green or black algae None
Thanks!

 

[Theo]

While I can't help on the source of the stains, I get them on my fiberglass stairs at the beginning of every season. I scrub them out with a Mr. Clean Magic Eraser then they're gone for the rest of the season. I'm not sure if this is an option for you if the entire pool is stained.

 

[DOMO]

Hi. Thanks for the reply. We use Magic Erasers on our waterline and they work great. I did try it on the stains when the pool was recently drained but they did not get rid of the stains. I am at a complete loss as to what is causing this and how to correct it.

 

[Butterfly]

What is the source of your fill water?

Have you had fill water tested for metals?

Did you previously use sequesterants?

Was the pH ever allowed to get high?

Was the pH ever allowed to get below 7?

Do you have a heater that contains copper?

What daily level pH did you maintain?

Please add your location in your profile.

Sorry for all the ?'s , just trying to help

 

[DOMO]

Hi. No worries on all the questions, appreciate the help. The water was from a spring water / pool water supplier. I did have it tested for metals, the report said none. I don't know what my daily PH level is, sorry. We are in Northeastern, MA. We do have a heater, but I don't know the answer to the copper question. We have a heater (Hayward natural gas) but have only run the heater a few times this yr. Not sure what a 'sequestrant' is, sorry.

 

[Butterfly]

If you don't have one of the recommended test kits, you need to order one. Also, the speed stir is very helpful, esp w/the CH tests. Test kits are compared in Pool School. The fav is the TF100, link in my sig. This will get you on the right path.


They said no metals, but it sounds like metals.
Try this, instead of just rubbing the vit C tabs on the stain:
Crush some cheap vit c tabs in a sock and hold it on a stain for a few minutes and see if it lightens.

When did you have if refilled with the new water ?

What are current test results? (The other tests did not contain FC or CC or TC. Also, there is no way to test CYA at 11. Sounds like they just made up a #)

Can you post some pics for us?

 

[Butterfly]

btw, did you have your fill water tested for metals? I mean the fill water that comes out of the water hose you use to top off.

 

[DOMO]

Hi again. SO sorry for the delay, we had a dual birthday party for the kids this weekend which took up a good deal of time the past few days preparing!

We did buy a better test kit this weekend, so I can now try to give you more numbers. PH was about 7.6 on Saturday.

We had it refilled with water on 5/18 and the test results I sent before were from 5/24/13. We did not need any top off water at the time.

That's disturbing to know they may have made up the CYA 11 number. Their test system is via Bioguard and provides a detailed printout. During that test, total and free chlorine were .7 and .6, respectively.

While buying the test kit and a few other things this weekend, we did buy 'Super Erase' stain remover at our local pool store. We applied it and have been running the pump/filter continuously since then. I can't yet comment on how the stains look as the kids' pool party was yesterday, but will take a look tonight when I get home.

Thank you again for your help!!