FYI, this type of favia is not typically a very fast grower. In fact its typically a very slow grower. This may not be the best coral for a grow out contest.
This place will also waterproof the sensor for you just in case. https://www.etcsupply.com/etc-prewired
Prices have gone up since I purchased though. I use rancos to even control vent vans in a couple media closets.
I know Norm still has a tank. Gresham is here as well. I'm sure lots of people would hook Ed up with coral if he ever returns. Anyone know if Lap still has his 300 gallon?
Cutting through the middle of that big head at this point is probably the best way to frag it at this point. What you should do in the future is make a ramp with 2 part epoxy. This way the acan has something smoothe to transition to and encrust.