Just got back from Boston today, and had a very interesting afternoon. I shut off the pumps so I could attach some of the frags I got on this trip. After I put all the frags in, i started all the pumps back up, and my Dart pump used for circulation refused to flow water. It was running, but there was barely a trickle comming out of the pump. Turned it off and tried to restart it.. nothing.. same problem. I figured there must be something wrong with the pump, so I decieded to take it out and look. The pump looked fine, the impeller was spinning. Put it back on, same problem.. the pump just did not seem to be able to generate enough pressure to push the water to the tank.
I decieded that something must be wrong with the pump, and replaced it with a spare DART that I had bought just is case any of my pumps went bad. Put the new one in.. SAME PROBLEM !!! Now I was getting really frustrated. Turned it on and off a few times.. nothing.
Two pumps could not have gone bad, so I started looking for other causes. It seemed that the pumps could not push the water up the pipe, so I thought that there must be an air lock of some sort developing in the plumbing. I took a mag pump and pumped in water to the tank, and tried to start a siphon through the circulation pump to try to remove the air. Got a good siphon going, and restarted the pump.. this time it worked !!!
As I went back to clean up and put things back in place, i noticed a dark blob in the sump. It was the bubble tip anemone that I was holding in my overflow box for the last 4 months. It made it way through the overflow box, and drain, into the sump and it must have got stuck in the ball valve of the intake. Thus blocking the intake and not allowing the pump to generate the pressure. The back flushing with the siphon managed to push it out.
It seems that every weakness in the system will eventually get exposed. I should have put a strainer on the intake from the overflow. Would have prevented disaster and hours of time being wasted trying to solve the problem.
sanjay.