One of the main reasons is to keep any extra resin away from my pump. Lay-up on a 20’ hull with two skins of carbon and some spots 4 skins in tropical heat will have to be fast so if a little extra epoxy goes on it will be bagged out into the felt, if the felt fills it will go into the reservoir. That is not the plan to suck epoxy into the reservoir like Jake says .........but when do things always go according to plan?

The resin that may go into the tank will just harden in the bottom. At some point if it clogs the reservoir you can cut the bottom off and add a new piece of PVC.

I used clear tubing from the manifold to the pump and resin checked the tubing to see if it melts. The tubing worked well and I actually peeled the resin off of it. I will also use the clear tubing from the mold to the reservoir so I can see if I have epoxy flowing out of the mold. The clear plastic tubing is about $5 for a 10’ roll and should be reusable because it will be in upwards bends so the resin will flow through it, not sit in it.

The water seal sounds good, and from what I hear, bongs had water in them but with the vacuum created on these systems it would suck the water right into the pump.