Presure Changes from Drain to skimmers

[MBar1958]

My pool has always blown air through the returns. But lately the pump loses pressure when I switch from skimmer to drain. The pool has two skimmers but without hooking anything up, it looses water when I switch to one or the other. It works fine when it suck from both the skimmers and drain. But as soon as I switch it to one or the other, the water in the basket starts going down and then I just get a trickle of water going through the basket pump.

[mr_clean]

My pool has always blown air through the returns. But lately the pump loses pressure when I switch from skimmer to drain. The pool has two skimmers but without hooking anything up, it looses water when I switch to one or the other. It works fine when it suck from both the skimmers and drain. But as soon as I switch it to one or the other, the water in the basket starts going down and then I just get a trickle of water going through the basket pump.

When air bubbles come out return lines, it means you have a suction side leak which is before the pump.
Sense pump looses pressure when switching to drain it's probably that pipe that has suction leak.
Some leaks will suck more air when pressure rises so when you switch to just one skimmer this causes you to notice it more.
When sharing skimmers & drain pressure goes down & will not be as noticeable.
You can call a leak specialist who can help you find and fix it. If you do it yourself it will be alot of work, unless you can live with it until it gets worse.