Is the water in your hot tub cloudy?

Cloudy water can be caused by either a mineral imbalance or by having too much organic matter in the water.

The first thing is to have the water tested for total alkalinity, calcium and pH. A combination of high pH together with high calcium or alkalinity will cause cloudiness. The solution is to add the correct amount of acid.

Cloudiness can also be caused by perspiration body oils cosmetics etc. dissolved in the water. This is a natural result of people using the hot tub and can be corrected by shocking (adding a greater than normal amount of oxidizer) and ensuring the filter is clean.
If the water is older than about 3 months it is not worth trying to shock the water. You will be better off by replacing the water with clean water.