Suction line sizing

[Mr. Fixer]

Murphy's law is in full effect here. I am decking out my AG pool. In the process, I've relocated the filter from the ground level to the deck. I upsized the piping between the pool and the pump (2hp) to 2" and temporarily used the standard 1.5" flex hoses at the connections. When I connected my Hayward bug vacuum the standard flex hose collapsed at the pump due to the increased resistance. I then replaced the 1.5" flex hoses with 1.5" spa hose and tried the bug again. The hoses held but my filter pressure dropped to about 5 psi. My inclination is to increase the size of the suction line but I'm concerned about putting in the T&M and ending up with the same issue. What do you all think?

 

[mas985]

Is the pump now above water level? By raising the pump, you have increased the suction at the pump which the flex hose is not meant to support. Also, is your current pump self-priming? Another problem if it is above water level.

 

[Mr. Fixer]

Is the pump now above water level? By raising the pump, you have increased the suction at the pump which the flex hose is not meant to support. Also, is your current pump self-priming? Another problem if it is above water level.

 

[Mr. Fixer]

Mark, Thanks for the reply. I went ahead and increased the 2" suction line to a 3" and eliminated as many bends as possible from both the new 3" suction line and the original 2" return line. My pressures are now back in line and the aqua bug works properly.

PS, The valved garden hose connection on the suction line, visible in the 1st photo, is for priming the pump. The check valve below the priming valve is there to keep the pump from losing prime when the timer shuts off the pump, which works as long as skimmer doesn't suck in the air due to low water or an obstruction (toys usually).