How to soften water in a Hot Tub?
"My water is running very hard at about 400-450 ppm and I am looking for a way to reduce this to acceptable levels. What do you suggest???"
It is very easy to harden water, but very difficult to soften water using chemicals available for pools and spas. The water needs to be softened before it is added to your hot tub, and water softeners typically use a multi-stage process to soften the water and filter out mineral impurities before delivering it to an external source (such as the plumbing lines in your house). If your water is really that hard, you might want to look into a water softener for your home. These units can be expensive, but they pay for themselves by reducing the wear and tear on your household appliances, such as washing machines, etc.
Distilled water is extremely soft, since there are no minerals transferred during the distillation process, but diluting your hot tub's water with distilled water can be a very expensive procedure. It can also be tricky to determine exactly how much distilled water you would need to bring your water down to acceptable hardness levels where you can begin to add pH adjusters and sanitizers.
So, if you have a water softener in your home, I would suggest leaving it on during the next fill of your hot tub.
The good news is that if you end up having water that is too soft, you can easily harden it by using a Calcium Booster.