How To Get Rid Of Hot Tub Scale (And Calcium Flakes)



A lot can go wrong when it comes to the chemistry of your hot tub water, some of which can lead to a case of hot tub scale.

While this isn’t dangerous to humans, removing it should be a priority so it doesn’t infect the plumbing and equipment.

This article will go over what exactly this scaling is, why it happens, and how to remove and prevent it for good.

What Is Hot Tub Scale?

Hot tub scale is an overabundance of calcium and magnesium in the water, so it occurs when chemistry is out of balance.

When the level of calcium is oversaturated, the water can’t hold it and it falls out of solution. This results in chalky, white deposits with a sandpaper texture to build up on the surface of the tub. 

This scale isn’t overly dangerous to the tub itself (and can be scrubbed out), it can do some considerable long-term damage to your hot tub pump, filter, or heater, as well as the pipes.

Why You Have Calcium Scale

You’ve identified your problem as scale, but what caused it in the first place?

Your Water Is High In Calcium

The water must have between 175 and 250 parts per million (ppm) of calcium in it at all times. When the calcium hardness (CH) levels peak over 250 ppm, scale begins to form.

The source water you’re using to fill up your tub might already have high levels of calcium in it (ie. well water).

Alternatively, by adding in calcium chloride to balance your calcium level, you may be unknowingly adding too much. Always test your water before adding chemicals so you don’t overdo it.

We also recommend using a pre-filter on your garden hose when filling up your tub. This will remove a lot of the calcium and minerals that make water “hard” to begin with, and you’ll be starting with better quality water.

You Have High pH Water

Water that is high on the pH scale is considered alkaline or basic. 

Over time, a number things get dissolved in the water – chemicals, minerals, and even organic matter. These are known as total dissolved solids (TDS), and they’ll remain in the water until it’s swapped out.

When the TDS level is high, so too will be the pH of the water. This will cause the TDS to fall out of solution and lead to scale issues in the tub.

For reference, a TDS level under 1500 ppm is considered safe.

You Have Heavily Contaminated Water

Any time someone enters your tub, it’s being polluted. 

Bathers are the number one polluters of hot tubs, and for good reason. Things like body oils, hair, lotions, makeup, sunblock, soap/detergent residue, and even skin cells can all end up in the tub from a single person. 

If you’re not keeping up your cleaning regimen, high levels of contaminants in the tub can contribute to scale.

These contaminants could also have high levels of phosphates that are transferred into the water. Phosphates will bond with calcium ions to create calcium phosphate scale issues. You can keep phosphates under control with a phosphate remover.

How To Remove Calcium Scale Deposits

You should fix your scale issue as soon as possible to stop it from getting worse. The longer it hangs around, the harder it will be to get rid of.

Here’s how you can remove calcium scale from your tub:

1. Use A Hot Tub Scale Remover

If the scale appears to be localized at the waterline, and the amount is minimal, you can probably get away with using a hot tub scale remover product. 

When added to the water, this product softens hard water and high mineral content, resulting in the removal of scale in the tub.

2. Clean And Scrub Your Tub

If the tub has a lot of scale throughout, you should thoroughly clean it and scrub down the walls and floor. 

You’ll need some elbow grease here, but scrubbing will help loosen the calcium deposits and make the flakes rise to the surface. You can then use a skimmer net to scoop them out, or let the filter catch them as the water cycles. 

Depending on how much scale is present, you may need to rinse the filter a few times so it doesn’t become ineffective.

3. Consider Draining And Refilling

If you have a major problem with calcium scale, draining the tub is the best course of action.

This allows you to not only swap out the offending water, but gives you full access to the tub’s surfaces for detailed cleaning.

The empty tub will reveal every area where scale is present, making this method the most effective for removing the offending material. 

How To Prevent Hot Tub Scale

The best way to get rid of calcium scale in your hot tub is to prevent it from forming in the first place. 

Use the following tips to your advantage so you’ll never have to deal with high calcium levels.

Keep Your Water Chemistry In Check

The importance of staying on top of your water chemistry can’t be stressed enough.

The main levels you need to keep in check are the pH (between 7.4 and 7.6), TA (between 80 and 120 ppm), and CH (between 175 and 250 ppm).

Chlorine levels should be between 1 and 3 ppm. If using bromine, you’ll need it between 3 and 5 ppm.

Keeping these levels in their respective ranges will prevent the water chemistry from getting out of hand.

Stick To A Regular Cleaning Schedule

Simply by following a weekly maintenance schedule, you can see where your water stands through testing and make adjustments so it always remains in check. 

Again, the more you use the tub, or the higher the bather load the spa is subject to, will both demand more frequent testing.

Cleaning the tub weekly doesn’t require much more than scrubbing it down, but make sure you use a soft cloth that won’t scratch the shell. 30 minutes a week can save you a huge headache down the line.

Maintain Your Filter System

A fully operational filter can be very effective in removing high levels of calcium that have fallen out of solution.

The majority of hot tubs use cartridge filters, and in order to keep them operating at peak performance they need to be rinsed every 2 to 3 weeks so that contaminants don’t build up on their media.

At the 3 month mark, soaking the filter in a deep cleaning solution for a day will help to restore it.

With regular inspection, you’ll be able to tell if the filter’s compromised in any way, and you can then replace the cartridge before any major damage is done to the tub.

What If It’s Not Hot Tub Scale?

Sometimes scale can be mistaken for other issues with the tub. Here’s a few things it could be if your scale removal techniques aren’t working.

  • Hot tub scum. Hot tub scum is a buildup of pollutants that show up as an oily presence in the tub and along the waterline. Running the jets will cause the oil to create a nasty froth that will require removal from the tub. Scum occurs due to inadequate sanitizing or filtration, or simply because there is a high level of metals in the water.
  • Algae blooms. Hot tubs are prone to algae breakouts due to 3 factors: a high water temperature, a smaller body of water, and high levels of pollutants. If algae forms, it could get into your pipes and equipment and you’ll have to spend hours fully scrubbing the tub and flushing the filtration system to get rid of it. The best way to prevent it from invading your tub is to use an algaecide once a week.
  • Mold or mildew. When a spa gets moldy, you’ll notice a funny smell and see things floating in the water. Mold comes in various colors (pink, white, black, green) and can be a common problem in tubs because of their warm temperature. Keeping the spa clean and cover washed regularly will help prevent mold from forming.

That’s All It Takes To Fix White Flakes

The white residue of hot tub scale is both preventable and treatable.

Regular cleaning keeps these deposits from building up and flaking in the water and filtration system. 

All you have to do is follow a strict maintenance schedule, be thorough in your cleaning, and you shouldn’t have much of a problem with scale.

Categories: Hot Tub Care, Hot Tub Problems