What do the installation instructions say?
The most valuable tip I can give you is: Read and FOLLOW *all* the installation directions. If there's anything in them that you're the least bit uncertain about, don't guess...ask. I strongly recommend that you have a chat with Vic Willman at Raritan (800-352-5630 x 6) about how best to wire it even if you don't think you need to...'cuz wiring it correctly for the individual installation (distance from the battery, manual or electric toilet etc) is critical to a trouble-free installation. As for whether to keep the loop... If the toilet is below the waterline--which it is when you're heeled whether it is when the boat's at rest or not--the answer is yes, you need a vented loop between the toilet and the treatment unit...and you'll also need a second one between the treatment unit and the thru-hull. (This is in the instructions, btw).
