Stained Vinyl Liner

[Cpagasky]

I've actually struggled with this issue going on 2 years now. I have an inground pool with vinyl liner, 18 x 36. I have a mysterious light brown stain that appears randomly throughout the pool. I don't believe its an algae but the local pool store tells me there isn't an abundance of metal in my water. I've used United Pool Stain Treat and it will remove the stains temporarily, but they return after a couple days and that product creates a gummy white material that clogs my DE filter. My water is crystal clear, but the overall appearance is horrible because of this staining. Here are my chemical amounts. Chlorine 1.5, TA 185, PH 6.8 CYA 30. I'm also not sure why I can't get my PH and Alkalinity to balance out.

Thanks for the help

[Watermom]

Before worrying about that stain, you need to get your pH up ASAP. Anything lower than 7.0 is acidic and can damage your liner. And, since 6.8 is the lowest most kits can't show, your pH may actually be much lower than that. Add a box of 20 Mule Team Borax (laundry aisle at Walmart) slowly to the skimmer breaking up any clumps. Wait a couple hours, retest pH and redose until you get it above 7.0. Once it starts moving, you may want to add 1/2 box at a time.

The procedure for lowering alk can be found here:

http://www.poolsolutions.com/gd/lowe...p-by-step.html

As far as chlorine goes, yours is a little low. Chlorine levels are based on CYA levels. With a CYA of 30, your chlorine should be between 3-6 all the time. (Take a look at the Best Guess chart in my signature below.)

Now, about the stain. Do you ever bring your chlorine up to shock level which for a pool with a CYA of 30 would be about 15ppm? If not, why don't you try doing that for a few days to make sure it isn't a type of algae. Test your water 2 or 3 times per day and each time add enough bleach to get back to 15. When you can go from sundown one day until sunup the next day without losing more than 1ppm, you'll know that there is no algae in the pool and you can let the cl drift down to 3-6. Then you'll know that the stains aren't algae and we can help you try a couple other things to get rid of them. But, the first thing to rule out is algae.

By the way, welcome to the forum! Glad to have you here!

If you tell us your volume, we can help you figure out how much bleach you'll need to add.

[Cpagasky]

Hey, thanks for the help, I"m going to stop at walmart today to get the Borax. After reading the procedure for getting the alk back to normail, I'm wondering if once I get the PH raised, what should my next step be? Should I try to get the alk in line or should I raise the Chlorine levels to see if the stain is algae?

[PoolDoc]

Do both.

You MUST keep your chlorine levels up or you WILL have problems.

Lowering the alkalinity takes time and patience. In any case, that's probably not the cause of the stains.

Try to avoid UCC products. They do work, but they tend to be 'black magic' like, in that there's always a price to pay for using them. That's one reason why I came up with, and why we emphasize, the BBB method: -- using as few things as possible in your pool greatly increases your chance for success.

[Cpagasky]

I got my PH up to 7.5 after adding the Borax, but my Chlorine seems to have dipped to near 1. I was going to try to elevate the chlorine to 15 to do the shock you recommended to make sure the stains aren't algae related. My pool has about 28500 gallons. How much bleach do you think I'll need to add?

[PoolDoc]

To go to 15 ppm on a 28,500 gallon pool with plain 6% household bleach, you need about 9 gallons.

But, I'm going to suggest something more cautious. The problem is that while high chlorine will often remove organic stains, it will tend to make metal stains WORSE.

So, before you take the whole pool up to 15 ppm, can you locate an area that is shallow, and has the staining? If so, take a synthetic (NOT cellulose!) sponge, and put it in a baggie that will fully enclose it. Pour in enough bleach to saturate the sponge. Then put on your old swimsuit and some plastic gloves and get in the pool (unless you can reach it from the side). Take the baggie to near the stain, open it, and quickly place the sponge against the stained area. Compress it somewhat against the stain, and wait 30 - 60 seconds. Remove the sponge, and see if the stain is better or worse.

[Cpagasky]

It seems that you were correct and the stain was in fact an algae of some type as after the first night with the Chlorine at 15 most of the stain disappeared and the filter pressure had gone up from filtering the dead algae, I'm guessing brown or black. After getting my pH to stabilize, I increased my Chlorine to 15 by adding the 9 gallons of Bleach. I've had trouble keeping the Chlorine at the 15 ppm level, I"m almost thru the third day and I've added an additional 7 gallons of Bleach to try to maintain that level. I will say that about 85% of the stains have been removed and I'm hoping that if I keep the level at a shock that remaining stain will be removed as well. How long does it generally take to kill an algae of this type?

[Cpagasky]

The Chlorine levels have been staying consistent with only 1 ppm lost last night. So it seems that I've eliminated the algae but there is still a small amount of stain remaining. Any ideas?

[PoolDoc]

Hold the chlorine up for at least 2 more days. You want to be sure the algae is completely gone, not just mostly gone.

Meanwhile, we need to see about your total alkalinity. It would be easiest to manage both your alkalinity and your chlorine if you have a Taylor K2006 or one of the few other complete kits with FAS-DPD testing. If you don't there's an Amazon link for the Taylor in my signature.

How did you get the 185ppm reading? (I'm asking, because I don't know how much to trust it.) If it's reliable, you need to try to hold your pH in the 7.0 - 7.2 range.

[Cpagasky]

I'm using the HTH 6 way test kit to test my alkalinity. I have one of the simpler taylor kits that I've used for chlorine along with some of the less reliable strips to test at the top levels. I need to order the better taylor kits but haven't done it yet.

As for my original problem, I'm thinking that I had an underlying stain that was compounded with algea, as I've kept the Chlorine levels in the shock mode all week and there remains a yellowish brown stain but the chlorine levels are no longer dropping overnight like they had originally.

Let me know if I should go ahead and get the taylor kit now, I was hoping to limp through with this one but at this point I'll get it if necessary.