United Chemicals PST-C12 Pool Stain Treat, 2-Pound

Works great, I poured it in our pool when the pump was off over night and woke up to no more stains. I got a bad bag of salt and it caused orange stains that we had for months and this product took them away

UPDATE May 17, 2018: OK, I now know with certainty how much phosphate this adds to your pool. After my experience described in my original review below, I used SeaKlear Phosphate Remover to get the phosphate levels below 250 ppb. Then I used one bottle of Pool Stain Treat to remove some residual stains, and it worked great, as usual. After a couple of days I re-tested for phosphates using the Taylor Technologies Phosphate Test Kit, and the levels were slightly over 1,000 ppb (in my 35,000 gallon pool). I used one quart of SeaKlear which took the levels back below 250 ppb (about "ideal level"). My recommendation is that if you use this product, plan on following up after a couple of days by using at least one quart of SeaKlear for every bottle of this you use (see my review on SeaKlear Phosphate Remover for tips on how to use it).Original Review:This works extremely well but may put the phosphate levels in your pool off the charts, literally. If you buy this, you should also buy a phosphate test kit and some phosphate remover (more on those later).I have a huge problem with leaves in the Fall and pollen in the Spring staining my white fiberglass stairs. I've been using this product for years to remove the stains and it works better than anything else I've tried. I shut the pool pump off and let the water settle for a few hours, then sprinkle some of this evenly over the stairs. They whiten before your eyes. I notice that the manufacturer has recently changed the instructions to specifically say NOT to use it this way, instead to pre-dilute, but I've never had a problem with direct application.This year I also had some pretty bad leaf stains on my vinyl liner as well, which this product removed from the area around the stairs, so I added some additional, a total of 2.5 bottles for a 35,000 gallon pool. Made the ENTIRE liner look like new, even the white plastic drain cover and skimmer openings. My pool looked FANTASTIC - clear, blue and sparkling - for a few days. Then, literally overnight, it was the color and clarity of pea soup. I had the mother of all algae blooms going on.Took a water sample to the local pool store and the phosphates (which are basically "superfood" for algae) were over 6,000 ppb - not sure how much over as 6,000 is as high as the test went! ("Ideal" level is 125 ppb.) Now, I'm not saying that all of those phosphates came from this product - they can come from many sources such as leaves (my original problem) and other pool chemicals and cleaners - and I probably had residual buildup from using it every year, but it's well known that this product will raise phosphate levels (see the other reviews). This last heavy dose must have put things over the edge and caused the algae bloom.It took almost three quarts of SeaKlear Phosphate Remover (available on Amazon for one third the cost at the pool store) to get the levels back below 250 and my pool is clear again. I also invested in a Taylor Technologies K-1106 Phosphate Test Kit (also on Amazon, and much more precise and accurate than the test strips) so I could cut the pool store out of the deal and stop getting ripped off. (See my review of the SeaKlear for some tips on how to use it.)Now that the pool has cleared up, I notice that there is again some mild staining on the stairs, which I think is from the algae bloom. I'll use this product again (judiciously) to remove them, but this time I'll be armed and ready for Phosphate Wars.

EDIT 9/11/2016: I moved, and now I have a gunite pool, and it doesn't seem to work at all. Our pool guy said that with the nature of our stains, there's nothing we can do, short of draining it and refinishing. (And even though the stains are evident, it doesn't look horrible.) But I'm going to keep the five stars for how well it works on vinyl liners and plastic stairs.This works great on removing stains. HOWEVER:1. It only removes stains where I apply it. In other words, when I throw it in, you can draw a line around the application area, and everything below that will be clean (I have a vinyl underground pool). But one inch beyond that area will remain stained. It's not something you can just put in, walk away, and have your whole pool clean, no matter how much you use. I even tried to brush it around with no luck. And it works so well, that the rest of your pool will look like garbage, and you'll have to go buy more to treat the other areas of your pool.2. It doesn't treat any vertical surfaces, unless you hand-apply it with a sponge and scrub them. I can put it on the water at my steps, and the horizontal parts will look great, and the vertical parts will remain just as stained.3. It will destroy the chemical balance of your pool. The package states it will lower your pH, which is true, but even worse is what it does to your chlorine, which can go from as high as 5 ppm to zero. So if you use this, you'll have to shock your pool afterwards, and raise the pH, so the cost is more than the $22 per stain bottle.One good thing about it being so strong is you can throw it in there no matter what your pool condition is and it will immediately work. Other stain products require your pool balance to be perfect, to only be applied at night, etc. Not with this stuff.Overall, this product is fantastic, via the 5 stars, but only if you have a badly stained pool, only if you plan to use multiple bottles of it if you need a large area done (don't do it at all otherwise), and only if you don't plan on using your pool for a few days, so you can a) do the stain treatment, and b) raise the pH and chlorine levels back to where they need to be.

This is a simple product that simply works! I have a fiber glass pool and it is surrounded by a forest of oak, hickory, gum and pine trees. Even with a cover on my pool leaves and straw find a way to enter. It only takes a dozen leaves on the bottom of my pool sitting there for 5 months to stain. Sometimes the inevitable happens and my pool gets dunked in leaves. I tried every product my pool supplier advised and I had no results. I tried calcium tablets in a sock with zero results. I broadcasted calcium tablets and had no results. I bought an attachment for my pressure washer that cleans concrete walks and drives. Also I purchased extensions so the cleaner could reach the bottom of my pool. I dropped 4 large chlorine tabs (3") into my pool and placed the cleaning head over the tabs. I washed for an hour with the tabs spinning in the cleaning head on the bottom of my pool. Results was dissapppinting! Finally, I bought 3 containers of United Chemicals PST-C12 Pool stain remover. I opened the first container and sprinkled it over and around the pool. I avoided the steps per directions. Within 10 minutes my pool turned cloudy and I turned my auto pool cleaner on. The next morning the cloudiness was almost gone and BAM!!!!!!!!!! The stain was gone!!!' This product was a miracle for me!