Remove Pool Rust Stains


For many owners, cosmetic appeal is one of the major charms of having a swimming pool. The aesthetics of your pool can be quickly blighted by unsightly rusting that can mark the plaster or vinyl. If you’re looking to remove pool rust stains, here are a few quick fixes that can help restore your pool surface to its former glory.


U.S_penniesFirst of all, it’s best if you can do things to prevent pool rust stains from forming in the first place. Keep metal cans away from the pool or in a separate eating area as the pop tops are notorious for falling to the bottom and rusting in as little as a day under chlorinated water. Hair pins are also a common culprit. Either encourage swimmers to take out their bobby pins before taking a dip or make sure you scour the bottom after a big party. Never use coins as diving toys in the pool because pennies rust easily.

If you are having stains that appear to come from the piping, this could be attributed to not having properly balanced water. When something like pH or alkalinity isn’t maintained, metals are leached from the plumbing system and end up deposited in the pool and stain the plaster or vinyl surface.

If you have a recurring stain underneath your plaster despite how many times you’ve removed it, you may have an errant rebar tie wire that is causing your walls to rust. That’s a much more complicated fix that you’ll probably need a pool professional to correct.*

With that in mind, here are a few suggested methods to remove rust stains.

Sock/Panty Hose + Dry Acid

urlPlaster/gunite/cement pools only

If you have a few small spots of rust, you can use a tube sock or old panty hose filled with granular acid like sodium bisulfate (dry acid) which is common in many pH decreasers. Add a cup of dry acid (wear gloves and protective eyewear) to the sock or pantyhose to keep it all in place.

Using either a pool pole if the stain is far down or a gloved hand, hold the sock over the stain or let it rest anywhere from 5-15 minutes, checking often. You can also use a stiff brush during the process as well as afterward to help remove the stain.

If you have an older plaster pool that has discolored over time, you may experience a reverse stain where the spot where you removed the rust becomes brighter than the area surrounding it. For this reason, be careful not to leave the acid on too long.

PVC Pipe + Dry Acid

Plastic_tubingPlaster/gunite/cement pools only

You can do a similar process, but with a 1.5-2 inch diameter PVC pipe instead of a sock. Use your dry acid like a pH decreaser or an ascorbic acid while holding the pipe. One of the benefits of using a PVC pipe is that you can also use liquid muriatic acid (make sure you use proper safety gear when handling this). With one end of the pipe over the stain and the other sticking out over the water, pour in your acid and hold steady for 30 seconds. Then begin to make small circles with the pipe to agitate the stain, increasing the rotation area as you go until the stain has faded.

If you have a stain on the wall of your pool, use a 90 degree elbow fitting so that you have one end out of the water.

Stain Eraser

All pool typesRS355CS-2T

For smaller rust stains, there are stain erasers that work both for vinyl/fiberglass pools as well as plaster/gunite/concrete. They’re made with a polymer and a built-in, mild abrasive that are meant to attack pool rust stains. These erasers can be hand-held for penny stains on pool steps or can be attached to a pool pole to erase all kinds of hard-to-reach blemishes.

Vitamin C Tablets + Brush

Plaster/gunite/cement pools only

Vitamin C Tablets are made of mild ascorbic acid and works well for cleaning pool rust. You can rub a large tablet over the surface and that will do the trick on most small, new pool rust stains. If you have a larger surface area you want to clean, crush up some tablets until they’re in a powder, sprinkle over the stain, and brush vigorously.

Stain Eliminator

C002837-CS20B2-2TAll pool types

If you have more than one or two spots that need treating, you can use a stain eliminator. These work to remove rust and copper stains from all kinds of pool surfaces. To use, make sure your pH levels are between 7.4-7.6 and that your alkalinity ranges between 80-100 ppm. Add the stain eliminator at the rate of 1 pound per 10,000 gallons into the pool water and run the pool for 24 hours with the filter circulating. Check your water chemistry afterward and adjust as necessary.

Many sites recommend that you lower your chlorine content to less than 1 ppm before using a stain eliminator so that it’s not competing with the product. After you’ve let the system run for 24 hours, shock your system to restore proper sanitation.

Additional Notes

  • *If you have a persistent stain in your plaster pool, there’s a good chance it’s caused by a rebar tie wire. To fix these, you’ll need a pool professional (or an adventurous DIYer) to cut out that section of the pool, cut through the rebar, and coat the ends with a rubber sealant, then pack the hole full of hydraulic cement. This will all need a plaster job after it’s all said and done. If you don’t want it to look like a desperate patch job, you’ll want to call someone who knows what they’re doing.


  • Keep in mind that the acid solutions won’t be helpful on vinyl as it can damage the surface.


  • Always watch your water chemistry, especially when adding something acidic to the water.
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