Like anthony tried to exPlain. I cant do it From phone
The spaflex has 1" pvc extended out on ends so that the pvc thats attached to hose slips inside bulkhead. Normally it would slip over bulkhead and be tight without requiring any glue. This is my dilema.
You have 2 types of spa flex:
Type 1: has "female" ends and both ends accept 1" PVC pipe or street fittings.
Type 2: has "male" ends like what you have and is designed to go into 1" PVC fittings and the bulkhead. It is tapered so it gets tighter as it goes in.
If you remember my 210 that I had downstairs, it had the kind that you have (type 2) and that was only held in place with teflon.
All of my tanks upstairs had "type 1" spa flexes and those as well were held in place with teflon and none of my tanks upstairs nor my 210 ever let loose.
Gluing them in place is defintely a better way to go and you should do what you feel safer doing but you do have a choice.
There is no spa flex that I know of that slips over the bulkhead.
For me, I just don't like not being able to remove my bulkhead. There should never be so much pressure that gravity plays a part. I've even had returns only held in place with teflon and didn't run into issues but I wouldn't do it at someone else's house. =)
I guess a bulkhead is a small price to pay at the end of the day if the drain let loose but I'm just sharing my own experience/experimentation.