How To Clean A Fiberglass Tub With Tough Stains

As an Amazon Associate we earn from qualifying purchases made on our website.

Fiberglass tubs are popular because they’re affordable, lightweight, and durable — unlike most ceramic or porcelain tubs. That all sounds great, at least until it’s time to clean them, and the very thought of that can make your back ache. So, how do you clean a fiberglass tub with tough stains?

To clean a fiberglass tub with tough stains, you need a commercial or DIY cleaner made with vinegar, baking soda, or hydrogen peroxide. Wet the tub and apply the cleaner to the stained surface. Let it sit for a few minutes, then scrub with a soft brush. Rinse the tub and dry it with clean towels.

Stains on fiberglass tubs don’t last long if you use proper cleaning solutions, and you can even remove caked-on rust and mildew stains with little effort. But no matter how tough the stains are, you don’t want to use abrasive scrubbers like steel wool. Let’s get started so you know how to clean your tub correctly and safely.

How to Remove Stains From a Fiberglass Tub

Woman cleaning the bath tub

It’s important that you pay attention to the dos and don’ts of cleaning fiberglass to avoid damaging yours or giving yourself more work in the long run. If you notice a stain you can’t seem to remove, it could mean the finish on the tub’s shell is damaged. In that case, you may need professional help for refinishing.

DIY Cleaning Solutions 

The following DIY cleaning solutions are affordable, safe, and effective at removing tough stains from your fiberglass tub:

Distilled White Vinegar

Distilled white vinegar (on Amazon) is efficient at removing soap scum, mold, and mildew stains. A mixture of white vinegar and distilled water will do the job and clear the dingy appearance.

Spray the mixture on the tub’s surface and scrub gently with a soft-bristled brush. You can use a medium or hard-bristled toothbrush for small areas and scrub lightly in repeated circular motions. Rinse the tub thoroughly and dry it with clean towels.

Baking Soda

The mild abrasive power of baking soda makes it effective at removing tough stains and grime from your tub’s surface without scratching it.

For small affected areas, mix the baking soda with a reasonable amount of water to make a paste and apply it to the stains. Let it sit for 30 minutes, then scrub gently and rinse the tub thoroughly.

But if your tub has a lot of stains, follow these steps:

  1. Wet the tub with clean water so the baking soda can stick.
  2. Sprinkle the tub with baking soda.
  3. Spray the baking soda with distilled white vinegar.
  4. Spread the mixture evenly over the tub’s surface once it stops fizzing.
  5. Let it sit for 30 minutes, then scrub with a soft brush to remove loose junk.
  6. Rinse the tub thoroughly and dry it with clean towels.

Hydrogen Peroxide

Hydrogen peroxide will cut through tough stains on your hot tub and disinfect it. A word of caution, though: You’ll want to wear safety gloves and goggles when handling hydrogen peroxide as it could irritate your skin and eyes. Here’s how to use it:

  1. Wet your tub and pour hydrogen peroxide into it. 
  2. Let it sit for 5 minutes to dislodge stains. 
  3. Scrub the tub with a soft brush and rinse thoroughly with clean water. 

Lemon Water

Lemons may be cheap, but you’ll be surprised at their natural cleaning power on tub surfaces. Cut the lemons in half and squeeze their juice onto the fiberglass tub surface.

Brush gently with a soft brush and rinse the excess lemon juice with hot water. Rinse the tub thoroughly with clean water and leave it to dry.

Ready-to-Use Cleaning Solutions 

You can turn to commercial cleaners if home remedies aren’t your thing. However, you’ll want to pick one designed specifically for a fiberglass tub. You don’t want abrasive chemicals that can damage the fiberglass finish.

The following ready-to-use cleaning solutions are safe for use on fiberglass:

Cleaning Method for Removing Tough Stains

A woman cleaning a bath

If you have tough stains on the textured bottom of your fiberglass tub, don’t fret. Here’s how to get rid of them:

  1. Carefully mix hydrogen peroxide and baking soda into a thick paste.
  2. Add a few drops of Dawn Ultra Dishwashing Liquid (on Amazon).
  3. Spread the paste on the bottom of your tub and let it sit for 30 minutes.
  4. Use a soft-bristled brush to scrub in circular motions.
  5. Rinse the tub and dry it with microfiber towels.

To vanquish hard water mineral stains from your fiberglass tub, follow these steps:

  1. Wet the tub with clean water and sprinkle the affected areas with borax (on Amazon).
  2. Slice three lemons in half and squeeze their juice onto the borax.
  3. Let the mixture sit for about an hour, then rinse it off.
  4. If the stains persist, apply baking soda paste on the affected areas.
  5. Let the paste sit for 30 minutes, then scrub with a soft-bristled brush.
  6. Rinse off the paste and dry the shell with microfiber towels.

If your fiberglass tub has rust stains and stubborn hard water mineral deposits, it may be hard to clean it with borax, vinegar, baking soda, or lemon. In that case, the best solution is to go for a commercial rust and limescale remover that’s safe on fiberglass tubs. Our favorite is this one from the CLR Store (on Amazon).

Follow the product instructions carefully to know the correct amount to apply. It’s also important you let it sit for the recommended amount of time before rinsing and drying the tub. 

While a commercial rust remover can effectively clean your fiberglass tub, it may also irritate your skin. Always wear safety gloves when handling the product.

How to Prevent Your Fiberglass Tub From Staining

Fiberglass tubs are durable and attractive if adequately maintained. To keep yours in a sparkling condition, avoid using certain abrasive cleaners and follow these crucial tips to prevent rust and scum from building up:

  • Wipe the tub with a towel after bathing to prevent soap scum from building up.
  • Watch out when using abrasive pads, so that you don’t scratch and fade the tub’s shell.
  • Don’t use hydrogen peroxide on colored fiberglass tubs, as it can fade the shell.
  • Rinse off the chemicals well with clean water before drying your tub.
  • Ensure proper air circulation in the bathroom, so that the tub doesn’t accumulate mineral deposits and mold that cause yellowing.
  • Clean your tub regularly with vinegar to prevent stains from forming.

Leave a Comment