Inline Chlorinator Install Question

I am replacing my inline chlorinator (the cylinder type you drop tablets into.) My question is, because it must remain upright, when screwing in to the filter exit, it may be either too loose or too tight ("snap!!!") So using teflon tape can make up for being too loose. Is there a rule of thumb for how many layers of teflon tape is proper and how to hand tighten without going one turn too many? (P.S. The chlorinator is twice as difficult because it connects to the filter exit with a "nipple" connector so I have to get TWO threads tight without cracking!) Thanks in advance for any help!

After giving it more thought, I am going to get two threaded 1 1/2" PVC adapters and a small piece of pipe and connect it with them. I can tighten both as tight as I want then glue the PVC pipe into the two open ends. I will mark the top so I know where to stop tightening if I have to remove and re attach in the future.