How To Handle Iron Stains In Pool Floors

large iron stain in an inground pool below a skimmer

As a pool owner you know the maintenance it takes to keep your pool in a clear and swimmable state.  Though it may only take an hour or so each week, it’s still time you need to take away from your family and other leisure activities to maintain your swimming pool.  Given the time you take it can be extremely frustrating when you notice staining in the pool.  When you see iron stains in pool you may think there’s something gone horribly wrong.  In this article we’ll talk about why you see iron stains in pool, and what you can do about it.

Why Do You Get Iron Stains In Pool Floors?

The first reason you see iron stains in pool is the obvious one. Iron stains will occur in a pool if someone dropped some metal in the pool.  Most often, sorry ladies, the culprit is a hair clip or bobby pin.  These are small and inconsequential enough that when you lose one it’s not the end of the world.

However, when you drop one in the floor of the pool and it sits there for a week or so, it’ll start to rust.  Then, especially if you have a white interior finish on your pool, the rust stain starts to show up.  If you’re lucky, the pin will still be in the center of the rust stain when you jump in to look for it.

How To Spot The Cause of Pool Iron Stains

When you find a bobby pin in the pool and that’s what caused your rust stain, it’s a simple solution.  Take out the pin, and then it’s time to attack the stain itself.  Before we talk about exactly how to go about removing a rust stain however, let’s talk about some of the other reasons a rust stain shows up in the pool.  

If you recently completed the pool, or had it refinished, you could have one of the rare staining culprits.  This is the tip of a trowel that broke off in the plaster process, or another small piece of metal that got into the plaster mix somehow.  The most common is a piece of a tool falling off and getting worked into the surface. This will cause a rust stain to eventually spread out onto the surface of the pool.  Unfortunately, there is no way to know if the culprit is the corner of a trowel, or the next potential culprit.

The next reason you have iron stains in pool is the rebar or a rebar tie is too close to the surface of the concrete / gunite.  Since this will also cause the same appearance on the surface of the pool plaster, you will now have to do some exploration to find out the problem.

circular iron stains in pool steps on an inground pool

How To Fix Iron Stains In Pool Floors

The first thing a pool professional will do is have you sign something.  Undoubtedly, there will be some sort of sign off for liability purposes. This will be related to how the repair will take place and what to expect when they’re complete.  This is to protect the pool company, so if your work is under warranty, read very very carefully.  

Chipping Around The Iron Stains

The pool contractor will drain the pool down and get to work chipping out the rust spot.  Once they remove the plaster in the area of the stain, it’ll become apparent if the iron stains in pool are coming from the concrete or if they were coming from within the plaster.  If the iron stains are coming from within the plaster, it’ll be time to patch the pool and refill. This is a best case scenario and will be problem solved.

Exposing The Rebar Ties

However, sometimes you’ll see the rust stain is clearly coming from the concrete shell of the pool. In that case, it’s time to get chipping with a small hammer to expose the rebar or rebar tie.  A perfect situation now would be to find that a rebar tie wire has made it’s way to the surface after being dislodged in the construction process.  Often however, it’ll be a bar end that sticks out and needs to be cut back.  They will chip out around the rebar, cut it off below the surface, then use a concrete patch prior to the plaster repair.  

Pool Patching The Plaster

In any case, once the pool plaster surface gets chipped out to remove a rust stain, you’ll be dealing with a pool patch.  If you have a white plaster interior, it’s not too difficult to repair.  The patch will always be a different color. However, since these patches almost always take place at the cove between the wall and the floor, they hopefully aren’t too visible.  If you have a pebble interior, sometimes the patch will disappear completely into the matrix of the interior.  Although, if you have a black interior finish for example, it’s very difficult to make the patch disappear.  

How To Troubleshoot Iron Stains In Pool Without A Professional

Don’t immediately go about chipping out the pool and exploring for a piece of exposed rebar. Before that it’s best to start by assuming some surface metal caused the staining.  If you clean the stain and it comes back, then it’s time to think about chipping out the interior.  

Vitamin C Tablets Or PH Reducer

First though, to get rid of iron stains in pool the easiest way to do it is to use vitamin C tablets.  These are ascorbic acid and for a small rust stain will clean the rust away without much effort.  Just take the tablet and use your hand to rub it into the stain.

If the rust is in a deep spot and you can’t get down there to rub the vitamin C tablets, you can use dry PH reducer in a tube sock.  Make sure you take proper protective measures, gloves, mask, and eye protection. While doing so, fill the bottom of the sock with PH reducer, and tie it off.  Then drop the sock into the pool near the rust stain. With the pole, push the sock into the location of the rust stain and hold it in place for 3-15 minutes.  

Combo Pool Brush

From time to time, move the sock off the stain location and brush vigorously at the stain.  You should see the stain cleaning up in a few minutes.  Assuming the stain is in a gunite or concrete pool, you may want to use a ‘combo’ brush  instead of the nylon. This will give your brushing some extra strength.  However, it’s important to never use a combo brush to remove iron stains in pool if you have a vinyl or above ground pool.  

How To Handle Iron Stains In A Pool Summary

Noticing iron stains in your pool should be a concern. However, there’s usually a simple explanation. The culprit is often a metal hair accessory, grill tool or broken off piece left behind by pool builders. Metal doesn’t belong in your pool and it will cause iron stains. Iron stains cannot be fixed using many common methods for removing stains without draining your pool.

To resolve these iron stains without calling a pool professional, remove the culprit. Then, apply vitamin C tablets or dry PH reducer. Lastly, try to brush the stain aggressively with a combo brush. If all else fails, call a pool professional that specializes in renovations. They will chip out the stain area and let you know the problem. It could be a broke tool or it could be a bigger problem with the steel used to construct the pool.