In the Southeast England, we have very hard water. This water is full of calcium and products that are very aggressive for your hot tub or pool. Not doing anything firs up your hot tub and pool equipment like cattle.
Those products will help you preventing this situation from happening.
It is important to achieve the correct level of calcium in your water, the levels of which will vary depending on where you live and where your water supply comes from. Soft water tends to be low in calcium and hard water tends to be higher. Every time you top up or refill your hot tub with fresh water you need to check levels of calcium.
The ideal calcium hardness level for a hot tub is between 100 -200mg/l. If the level in your hot tub is below this it could lead to corrosion damage. If you do find the level is low, then use a suitable Cal hardener to bring it up to the correct level. If the level in your hot tub is above this it can lead to the water appearing cloudy. As a result, calcium can be deposited on the tub shell, heater element, filter cartridge element and the pipe work within. To reduce this use Hot Tub stain and scale inhibitor to stop stain and scale forming.