I just want to thank Nitro and ChemGeek, and anyone else who built this body of knowledge... after renting a house in the fall with a "working" but unused hot tub, I started researching... and reading... and reading.
It's a 350-400 gal 2001 Mountain Springs Spa (now defunct, I believe) with a lot of jets that the owners bought second hand when they lived in the house, but none of their previous tenants had used it. After some initial fiddling and a cleanout with Ahh-Some, I determined that all the major parts (pumps, controls, heater) were operational, and it just needed some serious TLC.
So... working on hit off and on... after pulling all the nozzles (mostly Waterway mini jets), replacing about a hundred old o-rings, replacing a couple of missing jets, replacing the pump seals with new, non-leaking units, re-cementing a blower line to an air valve, fixing some of the shell frame that had rotted, and slowly accumulating all the supplies to start and maintain it using the TFP chlorine method, I filled it late last week, balanced the water, and commenced the final sanitizing. (I took one shortcut: after superchlorinating for 6 hours of so to 100ppm with 34ppm dichlor and the rest Bleach, I used peroxide to lower FC to 10 ppm to avoid another drain/refill in near-zero weather, then allowed it to rest and checked for resting FC consumption...)
I declared the tub open and ready to use late Saturday, but deferred the choice of first soak to my wife... and we took it for its inaugural soak before the Superbowl yesterday.
What a treat! So far, no issues, other than wanting to go admire my handiwork, and one tiny leak in a fitting between the heater and one of the gate shutoff valves. When Pump 1 is only on low speed, it's a slow drip... need to fix that to enable full use of all the jets.
Thanks for the knowledge! Without this forum, I'd have been at the mercy of the local shops and probably would never have undertaken the restoration.