I have a 2000 Sweet Water spa Palarmo model. it has air control valves to add air to the jets, thes valves all leak air into the system.

I also have a very heavy chemical smell when the pumps are on enough to burn your eyes and throat. The water is clear and and tests good. The temp of the water doesn't seem to matter even at 85 degrees it smells.

bad seals on the control valves are the likely culprit for the constant air induction to the jets, but you may also have a loose leaking connection on the bottom of those valves where the hoses attach.

A strong chemical smell is often the result of an imbalance of the water chemistry. Generally if you are using chlorine, and are getting a strong smell to burn the eyes, it's caused by chlorimines, which is used chlorine. If you shock your tub, you will "burn off" these chlorimines and should help resolve the burning eyes.