For a lot of years, we were allowed to tie wire the conductor to the rebar. That's a BAD method as the steel tie wire has a tendency to go away.
Mechanically, a split bolt is still acceptable, if you're using #4 rebar, you need a 1/2" split bolt (Like light bulb designations, rebar is sized by how many 1/8" increments - ie: #4 = 4 X 1/8 or 1/2")
ALL mechanicals are subject to failure, they are getting weaker the day you put them in. Add Chlorine, lime and all other chemicals associated with pools and concrete the subject grows quickly.
I gave up anything but cadwelds long ago, I've had to dig up too many pools where the other methods were used - NOT installed by me though. If you go with the mechanical methods, take a lot of care in the prep. www.erico.com
they can get nearly any mold to you PDQ