Do I need to put chemicals into my hot tub?
Its usually just me in the hot tub. Are they really necesarry. Ive refilled my hot tub using water alone 6 weeks ago, and so far no problems. I usually decide to change the water when it gets cloudy or smells funny. What do you think. Am I good, or just going to have problems down the road that I have yet to find out about.

YAH
well, just like a pool, water in a hot tub needs to be treated. acid alone could generally clear out the cloudiness without having to waste water and refill your hot tub frequenty, and the smell maybe stagnate water. there’s special treating for the water in your hot tub. if you can find a leslies or another pool place, ask them about anything special that neesd to be done
Chlorine, available as powder/liquid
Keep the chemicals balanced. Use a sanitizer (bromine is the choice for spas). You’ll severly shorten the life of the heater and other components if you don’t balance the water.
you should keep the water balanced. if you change out the water every so often it may not cause any problems, but I don’t think I would want to soak in your bacteria infested hot tub! What do you think that funny smell and scum is?? at LEAST add chlorine!! add a few tablespoons every time after you use it and it should be fine.