New member - Stained Steps and Walls

[Nate337AZ]

Hi everyone,

New member here, but I've read the forums for a couple of years. I'm having trouble with brown stains on the steps and walls of my pool. It initially started on the steps, and recently has become noticeable on the walls as well. See the pictures below. What's causing these stains and how can I get rid of them? The plaster is about 3.5 years old.

Here's the chemistry readings as of this afternoon (using a Taylor K-2006 kit):
FC 5.5 ppm
CC <0.5 ppm
pH 7.7
TA 100 ppm
CH 480 ppm

I couldn't get a CYA reading because I just ran out of the reagent. I'll order more.

One other note that may or may not be related: the pool seems to need a LOT of acid. I usually have to add 0.5-1qts of acid every 2-4 days, and even then the pH is usually between 7.8 and 8.0 when I test it.

 

[pooldv]

Welcome to TFP!

Rub and hold a trichlor puck on it for a while. If it is an organic stain it will lighten or go away.
Rub or hold a vitamin C tablet on it. If it is metal it will lighten or go away.

If those don't work then it could be calcium scale.

 

[YippeeSkippy]

Have you used algaecides that contain copper? How do you sanitize your pool?

Quick way to test if the stain is organic or metal: hold a chlorine puck against stain and see if it helps lift it? Also do the same but with vitamin C tablets. If the puck lifts it it is organic staining. If the Vit C does, its metal staining.

 

[Nate337AZ]

Thanks for the suggestions, I will give them a shot tonight. How long do I need to hold the tablet on the stains? Is a few minutes OK, or does it need to be on there a couple of hours or more?

I've never used an algaecide, only chlorine (trichlor tablets mostly, occasionally liquid chlorine).

 

[YippeeSkippy]

By about 10 minutes or so you should know if it is working.

 

[Nate337AZ]

OK, so I tried both the Vitamin C and the chlorine tabs. The Vitamin C didn't seem to do much, and the chlorine looks like it removed maybe a faint ring around the tab. Definitely not a night and day difference, but it's noticeable. So if chlorine will get rid of the stains, do I need to raise the chlorine to shock levels for several days?

 

[pooldv]

Yes, and brush the spots. It doesn't have to be all the way too shock level but, it is probably going to be several weeks, not days. Good news is that is safe to swim with chlorine levels up to shock level for your CYA. Chlorine CYA Chart

Keep in mind that the PH test doesn't work correctly above 10 ppm. So, you'll want to let FC drop once a week or so to test.

 

[Nate337AZ]

Yes, and brush the spots. It doesn't have to be all the way too shock level but, it is probably going to be several weeks, not days. Good news is that is safe to swim with chlorine levels up to shock level for your CYA. Chlorine CYA Chart

Keep in mind that the PH test doesn't work correctly above 10 ppm. So, you'll want to let FC drop once a week or so to test.

Well I just got in the R-0013 reagent for the CYA test, and my pool tested >100ppm. I guess it's been longer than I thought since the last time I checked CYA. Anyway, I'm assuming I need to do a partial drain and refill to get the CYA down before I try to shock the pool for multiple weeks? What should I target for CYA?

Also, I bought some powder trichlor-based shock at the pool store. I'm thinking I should probably just be using liquid chlorine to shock it, to keep the CYA in control, right?

Thanks for all the help so far!

 

[YippeeSkippy]

Also, I bought some powder trichlor-based shock at the pool store. I'm thinking I should probably just be using liquid chlorine to shock it, to keep the CYA in control, right?

Yup, liquid chlorine all the way baby! Your CYA will only rise again more so with the addition of granular or puck products.

 

[Nate337AZ]

Yup, liquid chlorine all the way baby! Your CYA will only rise again more so with the addition of granular or puck products.

Thanks. So should I be shooting for a CYA of 30-60 ppm before I start the shock?

 

[pooldv]

What is it now? Anywhere in that range is fine.

 

[YippeeSkippy]

During a SLAM procedure, you'll only want the CYA about 30 so that your chlorine requirements are lower.

Then when the pool is again pristine and you've passed the OCLT you can raise the CYA up to the higher level your AZ sun requires.

Since it doesn't appear that you have a SWG, you can aim for about 50 and see how that works for your chlorine. Remember that the higher the CYA, the higher the chlorine requirements. Don't use powdered products that are going to "secretly" also add to your CYA. It becomes an insidious problem.

Please see this link: Pool School - Chlorine / CYA Chart