Be aware and take hot Tub water purification seriously. this is an important message. It is what we inhale or breath in. Whether it be chlorine, bromine, ozone, legionella, etc., it is all about what gases off of the water. What you smell is a dead give away your pH is out of balance.
Keep your water clean, in balance and sanitized regardless of your prefered method of purification. This is a condition of the good, better and best Hot Tubs regardles of their manufacturing differences.