I finally was able to do a freshwater test the other day.
Filled the tank and sump with water and turned on the pumps.
I went around my tank 2 or 3 times checking for unglued fittings, looking at the couple of hose clamps, making sure they were tight, bulkheads, screwed fittings, etc.
So I figured everything was cool.
After the tank was full and running for a half hour or so, everything seem stable, I made a cheeseburger run.
Was gone maybe 25 minutes. Sat down and ate my lunch.
Went over to the tank to check again for leaks and saw a little water on the floor directly underneath the manifold end cap.
So I reached down to see if I could feel water dripping from it and I even gave it a little pull.
I did this while the Reeflo Snapper/Dart pump is running.
The cap started to move a hair, then all of a sudden it tried to come off completely, with a lot of pressure.
There was a actual brief moment of panic.
I was lucky that I was able to push it back on and run around to the other end and shut off the pump.
If it would have come off, it would have been like a charged firehose blowing water out.
