Making a pump SELF PRIMING

Like the title says, I had the need to create a self priming pump. My current problem that I have been dealing with is a submersible pump that heats my water to 90+ degrees. During the hotter months I have had it on a timer to give the system time to cool down. With the stuff I got with the fish farm, there are numerous pumps. Some of them are way too big, and others are embarrasingly small. Today I tank tested a bunch of them to find the actual flow rates of them. All of the self priming pumps are way too big for even the largest of fish tanks. We are talking 260 gallons per minute.That's just over 15,000 gallons per hour. They had some serious gallons at that fish farm...I have four of these pumps.

Anyway, I need a small pump that will pump around 300gph at ten feet of head, but one that is not submersible. I also need to draw up from about three feet. That means I have to have a self priming pump. I found several pumps but none were self priming, so that gave me the task at hand. To convert a pump to be self priming.

Here is the parts break down and a completed trap.

And the trap installed on a mag drive pump.

And here is a pic of it in my "laboratory" in the test tank. It would run great while the tank was full. The initial start up was instantanious with the pump about six inches above the water level. At three feet above the water level, it took about thirty seconds to start pumping. After it pulled the water collumn up, it ran like a champ.

Tomorrow, I have to test the other pumps for operation at eleven feet of head. The green mag drives are rated for 20 feet of head, but I didn't find a rating for the others.

Good idea. I was looking for a flapper check valve but I could only find one that was spring loaded. I am going to be going to my wholesaler at the end of the week and figured I would see if they have flappers in 3/4 size. If not I will look into the foot valves.
Tanks,
Ron

Oh, by the way, I meant to add in the original post the theory behind this thing. The idea behind the trap is to keep water in the pump in the event of a shut down. Centrifical pumps require water inside them to pump. The trap keeps an amount of water in the system for this. When the pump restarts, it only has to process the air in the pickup tube before it runs at full capacity.

I need to pump from above the water level. When pumping from below the water level, the water pressure keeps the pump supplied with water when the system shuts down.