Have you noticed a chalky white film, white flakes, or a rough texture on surfaces in your hot tub? If so, there's a good chance you're dealing with calcium scale from hard water. Calcium scale is not only unsightly, but it can also cause damage to your hot tub. In this article, we'll look at what calcium scale is, how it happens in your hot tub, what risks are associated with it, and how to handle it.
Check if you're dealing with calcium scale
Before you continue reading this article, be sure you know the source of your scale is due to high calcium. Other types of scale can be the result of unbalanced water from high alkalinity or pH, high stabilizer or high TDS (total dissolved solids); the best way to rule these out is to test your water yourself or at a local pool or hot tub store.
Rule out biofilm
If you're seeing white flakes in your hot tub, there's also a chance you could be dealing with biofilm; here's a way to tell:
- Fill a cup with water from your hot tub (around 250ml)
- Add roughly ½ teaspoon of bleach to the cup and stir
- Wait 30 minutes
If, after 30 minutes, the white flakes have dissolved, you likely have biofilm, and if not, it's likely calcium scale buildup.
Slimy water, discoloured bubbles, or a strange odour are also signs you're dealing with biofilm. If you suspect this may be the case, check out our article on identifying and dealing with biofilm.
What causes calcium scale?
When water is too hard, minerals start to collect on surfaces in your hot tub, leaving a white chalkiness behind - this residue occurs more easily in hotter water - your heater and pumps are at the greatest risk. They can suffer reduced efficiency and eventually damage.
Hot tubs, in general, are at a higher risk for mineral scaling because as water steams off the hot tub and evaporates, it leaves minerals behind, creating harder water. It's crucial that you take care of hard water to prevent costly damage - if you're noticing scale, take action now.
Signs of hard water
- Cloudiness or foaming
- Chalky white film
- Rough texture on surfaces
- Dry flaky spots
The good news with solving a hard water problem is that it won't just keep your hot tub working longer; it makes maintenance easier - less sanitizer (chlorine or bromine) and more stable chemical levels. Dealing with hard water can be simple if you know what to do.
6 tips for dealing with hard water
Add fresh water
While there's no way to remove calcium and other minerals from your hot tub water, adding fresh water can lower the overall hardness. If you have a soft water system, you can drain some water from your hot tub and add softened water. Be careful to not make your hot tub water too soft, as this will lead to minerals being pulled out of your hot tub components and equipment. If you don't have access to soft water, you can use a pre-filter.
Use a pre-filter
A hot tub pre-filter is a garden hose attachment that removes hardness from water by using ion-exchange resins, which produces softer water. The First Step Clean-N-Fill uses a 5-stage filtration process to purify and soften source water. The bonus is that a filtration process will also make water chemistry easier to maintain (think of it like using a Brita filter to fill your hot tub).
Use a stain & scale protector
Depending on your source water, a pre-filter may not be enough to lower your water hardness below the recommended 250 parts per million. If your water is still too hard, add a stain and scale protector to your regular maintenance (just a capful each week).
Replace your water regularly
As we mentioned earlier in the article, as water evaporates from your hot tub, it leaves behind minerals which make the remaining water harder. If your source water is hard, topping off your water without a pre-filter will also add hardness. If you have hard water, you should aim to change your water quarterly.
Clean your hot tub between water changes
When you empty your hot tub for a refill, clean all the surfaces to remove any scale that has built up. Be sure to flush your lines with clean water so that you start with the freshest possible water (and remember your pre-filter).
Keep your water chemistry balanced
High alkalinity and pH will reduce your water's ability to hold minerals, causing them to build up on the surface of your hot tub and inside its equipment. Check your water chemistry a few times weekly (depending on its use).
Managing hard water can become simple and routine if you follow the above steps. By pre-filtering your water, checking your chemistry regularly, adding a stain and scale protector and replacing your water quarterly, you can make maintenance much easier and protect your hot tub.