Brown swimming pool water is usually a sign of high iron content. Pool water might suddenly turn brown after adding chlorine or muriatic acid, as it causes the iron to oxidize and basically becomes rust.
Fix this problem by shocking the pool with a non-chlorine-based shocker, then scrub all the surfaces with a brush. Now, backwash your pool and add a flocculant, this binds with iron and will accumulate on the pool floor. Now you can use a vacuum to remove this residue while your pump is set to “waste”
Heavy rain and flooding can also be the cause of brown pool water, and it is a much easier fix, we will look at that in this post as well.
Brown pool water that is caused by high iron can be tricky to fix, and it is advisable to try some other methods that might be a bit easier if your case is not too serious.
Let’s look at the cleaning process for high iron content in more detail and then we will look at some easier methods of cleaning brown (high iron) pool water.
First, make sure you know what is causing the brown water
There are two main causes of brown pool water.
- Just Plain Mud. If you have recently had heavy rainfall or flooding of any kind, then your problem might just be that your pool is full of mud. This is a relatively easy fix.
- High Iron Content. This is where treatment becomes complicated. Brown swimming pool water is usually a sign of high iron content. Water from boreholes and wells often have high iron content naturally and it is harmless to people. Pool water might suddenly turn brown after adding chlorine or muriatic acid, as it causes the iron to oxidize and essentially becoming rust.
TIP: To make sure that iron is the culprit, use an iron test strip to check if your iron content is too high. The iron content in your pool water should be below 0.2 ppm (parts per million). You can also take a water sample to a local pool store and ask them to test it for you.
Cleaning brown water caused by mud.
The mud accumulated in your pool will work its way out automatically through your pool filter, but you will need to put in some extra work to get there.
- You will want to have your pool pump running overtime. Your pump has a lot of work to do, so have it run as much as possible during the cleaning process. Run it around the clock if you have to. (And if you can afford the power bill)
- Scrub the floor and walls to loosen the mud. This will help your pool cleaner to suck it up easily and will drastically reduce the time this cleaning process takes.
- Backwash as often as you can. Your filter will be clogging up fast, so be sure to backwash your filter as much as possible, twice a day should do, especially in the beginning. Neglecting this can put a lot of strain on your pump and possibly damaging it.
- Back to normal. Once your pool water is clear, you can set your pool pump back to its normal timing and reduce backwashing to weekly.
How to clean brown pool water caused by high iron content
Before you do anything…
Do not add chlorine! If you have high iron content, chlorine won’t help to make your water clear. As a matter of fact, it will make it worse. Chlorine will oxidize any iron in your water, turning it brown/red.
- Shock your pool using a non-chlorine based shock product. This will destroy contaminants in your water.
- Scrub the pool walls and floor. This loosens all the iron particles and will help with the next step.
- Add a flocculent. Flocculent is a compound that will attach itself to the iron, and pull it to the bottom of the pool. You will need to read the instructions to figure out how much you need to add according to your pool size. Leave the flocculant overnight to do its thing.
- Vacuum the floor and walls. Before vacuuming, set your valve to “waste” so that the iron isn’t pumped back into the pool while you vacuum it up.
There are also some other ways that you can try that are easier and might work for more mild cases. Let’s look at those next.
DIY Cotton Filter
This is an old-school trick used by many pool pros! It is mind-blowingly simple. Let’s go through it quickly.
What you will need:
- You are going to make a cotton filter out of, well cotton. If you want to be lazy, rip up an old pillow, and use the stuffing instead.
- A large juice or water container, at least 1 gallon in size.
- Hose clamp.
- Duct tape.
- Drill to make holes in the container. Or you can just stab it with a screwdriver.
- Hose, or a PVC pipe that matches the container opening to your pool outlet.
With all of the above items, you can build a simple cotton filter that does a great job of trapping iron and rust.
Here’s how to do it. I recommend that you follow the steps while watching the video below.
- Step 1 – Drill holes (or stab) at the bottom of the container.
- Step 2 – Stuff the container full of cotton.
- Step 3 – Connect the outlet to the container using a matching PVC pipe or hose and the hose clamp.
- Step 4 – Once it is all connected up, leave the DIY filter in the pool, and run your pump on “bypass” mode. This will bypass the pool’s sand filter so that there is enough pressure to push the water through your new DIY filter.
- Step 5 – Leave the pump to run as long as you need it to. You might notice a difference in the pool color within as little as a day.
Put a Sock on it
Literally, put a sock on it. This is basically the lazy man’s version of the DIY cotton filter.
Use an old sock (preferably a thick one) and attach it to the end of the outlet into your pool. you can use zip ties, hose clamps, or duct tape.
Leave it to run like that and switch out the sock with a clean one daily. The sock should catch iron and rust particles and after a few days, you should start to notice the water getting clearer.
Watch the sock method in action in this video I found on YouTube.
Is Brown Pool Water (Iron) Safe to Swim In?
Water with high iron content is safe to swim in, as a matter of fact, most borehole water is safe to drink straight out of the ground even though it is usually very high in iron content.
However, water that is brown with high iron content is not good for your pool. This iron will oxidize and stain your pool walls, sometimes permanently, leaving your pool unsightly even when it is clean.
Conclusion
Brown pool water, even though it is safe to swim in, is unsightly and can leave stains on your pool walls that are almost impossible to remove.
There are two main causes of brown pool water, high levels of oxidizing iron, or just plain muddy water. Simple adding chlorine to high iron content water will just cause that iron to oxidize and your water will become brown.
There are a few ways to fix this, depending on how serious the problem is.
Muddy water can be fixed by running your pump on overtime and frequent backwashing.
You could tackle the high iron content problem by using chemicals, or you could build a DIY cotton filter, or even use a sock to catch iron particles. Hell, you could even use all of the above together for faster results.