How To Remove Moss Killer Stains From Concrete {Home Remedies & Store-Bought Products}

Are you seeing those little orange stains scattered on your concrete?

Did you apply moss killer to remove the pesky moss and now you’re left with something even worse? In this article, we’ll find out how to remove the moss killer stains from concrete.

How To Remove Moss Killer Stains From Concrete

There are many home remedies involving vinegar, baking soda and lemon juice to remove these stains. Sometimes we have to resort to store-bought products containing muriatic acid or other chemicals to remove these moss killer stains.

Does Water And Soap Remove Moss Killer Stains?

You can try water in a bucket or a pressure washer with soap, but chances are that this method is not going to work. A pressure washer is a good idea, but scrubbing is going to work better. Ditch the soap because there are better ways to get rid of moss killer stains.

These stains are basically rust and soap doesn’t remove rust. Dish soap works better than regular soap, but most people recommend using dish soap as a partner to something natural. A salted potato, believe or not, helps with dish soap to remove these stains.

Do you want to cut a raw potato and try it out or would you like to read further to see if there’s something better?

What’s The Best Way To Remove Moss Killer Stains on Concrete?

It’s hard to say what is best in your situation. It’s best to attack these stains as early as possible. In my house, there’s a spray bottle filled with 50% vinegar and 50% water. I use it on everything from cleaning the dinner table to the bathroom.

  • Dilute vinegar with water 50:50
  • Apply it with a spray on the stain
  • Scrub lightly with a hard brush
  • Rinse
  • Repeat

Don’t give up after just one attempt. Try it a few times. If this doesn’t work, you can use vinegar with other household items such as lemon juice or baking soda for tougher stains that won’t budge. Don’t worry, we’ll get rid of them. Let’s keep going.

Why Does Moss Killer Stain Concrete?

The moss killer you bought worked great for getting rid of the moss that was infesting and sticking out of your concrete. Job done. Not really. What your left with are orange stains all over the place and a confused head that needs scratching.

The stains are rust caused by the iron in the moss killer. It’s also known as ferrous sulphate which contains iron. Magnesium, copper, zinc, nitrogen and potassium are also included in the solution. They all play a hand at staining concrete, but iron is the main culprit.

Iron mixes with water and permeates into the concrete. Now there are orange stains that don’t want to go away. This means water and scrubbing is not going to cut it. We need a solution that is acidic to combat moss killer stains.

Which Products Work To Remove Moss Killer Stains?

There are many products on the market directed at removing rust stains. They aren’t specifically designed for moss killer stains, but’s that ok. Lets try two different products and see what happens.

Concrete Rust Remover

This product works on rust and fertilizer stains as well as battery acid stains. It’s meant for driveways, walls or anything made of concrete. There are no phosphates in this powder. If you follow the directions and mix it with water, it will form a gel.

  • Clean the dirt of the surface first.
  • Apply the powder and water gel solution that you’ve mixed (3 tablespoons to 1 cup of water).
  • Spread it generously on these orange spots.
  • Let it sit 15 minutes.
  • Wash it away.
  • Repeat the process again if the stains haven’t completely gone away.

Try scrubbing with a hard brush if the stains do not simply wash away. A pressure washer is not necessary, but does help.

Iron Out

Iron Out is another popular product that contains:

  • Sodium hydrosulfite
  • Sodium carbonate
  • Sodium metabisulfite
  • Citric Acid
  • Sodium sulfite

The process of using Iron Out involves mixing 1 cup of this liquid solution with 1 gallon of warm water. Once the surface is cleaned, you can apply this solution with a brush or sponge. Scrub until the stains are gone and rinse it out. Repeat the process once more if you still notice some stains.

Does Lemon Juice Remove Moss Killer Stains?

Some people try lemon juice and say that is doesn’t work to remove moss killer stains. Are they using lemonade or lemon juice in a bottle? How about real lemons?

It seems that more people report that real lemons work better than lemon juice. Cut them into chunks and scrape them all over the stains. Use a toothbrush or hard brush and start scrubbing. Wash if off completely with water because they can leave stains as well if you don’t act quickly.

Can Apple Cider Vinegar Remove Moss Killer Stains?

It seems that ACV or Apple Cider Vinegar is the cure-all for every problem that ails us. We can’t prove any of that to be true, but we can say that the acid in ACV is strong enough to counteract the iron and rust stains that you’ve got on your concrete from that moss killer.

ACV is not cheap and should be diluted 50:50 with water. White cider vinegar or regular vinegar is better because they are clear. Either way, this is not something we recommend that you let sit before rinsing off. You attack the stain with it and wash it off immediately to prevent more stains.

Can I Use Bleach on Moss Killer Stains?

We sincerely hope you don’t use bleach. This is a strong chemical that can not only harm your concrete, but you as well. The stains may not go away and could permeate even deeper, making them next to impossible to remove.

You look in your closet and pull out the toughest chemicals to fight moss killer stains. You may end up with worse stains and a headache, itchy eyes or skin burns. This is not the right approach.

What Is Muriatic Acid and Can It Remove Moss Killer Stains?

Muriatic acid is another name for hydrochloric acid. It isn’t bleach, but it’s just as hazardous if it gets on us. The good news is that it works to remove moss killer stains. You will need to dilute it as much as 40 parts water to 1 part muriatic acid.

It works well on all concrete surfaces and used commercially for this purpose. It will cause damage to the lungs and skin. Wear a mask, gloves and cover your exposed skin. If you don’t wash it out completely after it does the job of removing moss killer stains, it could etch your concrete.

Frequently Asked Questions:

Which Products Contain Muriatic Acid?

You can actually find muriatic acid in toilet bowl cleaners. These solutions are premixed with soap and water. They usually look dark blue or green in color. You can apply this to the stained concrete and wait 2-3 minutes. Scrub with a bristle brush and you’ll see the solution foaming up. Rinse thoroughly and you should notice that your moss killer stains are removed.

Why Did Moss Killer Stain My Concrete?

The iron in the moss killer solution remained on the concrete for too long. Rain or wet conditions caused the iron to settle into the concrete. It dissolved and penetrated into it. Your concrete dried up and you were left with orange stains.

Other Moss Killer Removal Tips?

  • The sooner the better. Attack the stains and don’t leave them until tomorrow. The faster you act, the better the chance of not needing to rinse and repeat.
  • After applying moss killer, wash it out with cold water so it won’t set for the long-term once it has done its job of killing the moss.
  • When using any remedy, start with a small section first. Go after one orange spot and see how it works before attacking the entire driveway with one swooping attempt of getting rid of moss killer stains.
  • Rinse out your chosen remedy thoroughly before trying another. Some of these chemicals will not react well with each other. Sometimes we get carried away and start applying all of the above at the same time.
  • Follow the instructions on the product labels. Don’t make it up on the spot. They have tested this out many times before writing them on their packaging.
  • Scrubbing super hard may not do much more than hurt your shoulder. Apply firm pressure, but there’s no need to overdo it with intensity and vigor.
  • Stay safe. If you’re handling muriatic acid or acidic solutions, it’s best to wear gloves and eye cover. A mask is also a good idea.
Amy Enrich

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