I'll need a new multiport and chlorinator also

When I put in the heat pump I suppose I should replace the 10 year old parts when I build the pipe system. Whats the deal with the off line chlorinator? I hadn't heard of that before. And who makes a good multiport valve for my de filter??? Thanks for the help.

18x36 inground pool
about 10 years old
I bought a new filter last year- fns plus 36
I am purchasing a heat pump
I will likely install it myself

Since you have a Pentair (Pac Fab) filter, you will need to get their valve. It will just attach to the bulkheads on the tank (just unscrew the existing valve at the tank fittings) with no modifications.