The hot tub is up and running as of Thursday evening.

Christmas morning, Elif finally got a chance to try the hot tub. At some point right before or soon after she got it, the locking ring on the filter split, spraying water all over the area under the hot tub. GFI worked and tripped the breaker.
Luckily Justin was around and had most of the water vacuumed up by the time I got back from 10:30 Mass.
I couldn’t find the exact locking ring online so I had to wait until Tuesday morning. I called an online spa parts place out in OK and talked to the support person. I mistakenly thought the filter parts diagram they had was showing a model very close to mine so I ordered it.
It showed up on Thursday and, sure enough, it did not fit. In a last resort moment, I drove down to Feeley’s and as soon as Mark saw the broken ring, he said, “That’s a Rainbow. I think I have one left in the back.” And he did, and it fit and it was $15.
Mission accomplished.
Here are some pictures Justin took after the failure.