Air trapped in filter

[jda]

Hello, I have a pentair pump / filter. This is my first pool. When I brought the water about half way above the skimmer, I primed the pump, bled the air, and noticed that I was reading zero on the pressure gage. After several tries, I looked in the bottom of the skimmer and noticed that the plastic fitting on the bottom that hooks up to the return hose only had a opening of about 1/4 inch. I thought it was just a manufacturing problem and opened up the hole with a small file as close to "full open" as I could. This seemed to work; the pressure increased to about 7 psi, and I obtained a very good flow. Also, there was no longer signs of entrained air out the discharge into the pool. However, I noticed that I could bleed quite a bit of air when ever I opened the relief valve. I this normal. I was thinking of lower the flow rate slightly using a ball valve I installed on discharge side. I also installed a ball valve on the suction side as well. I made sure the suction fittings were tight. Please advise.

Thanks, Jeff