Pulling from skimmer vs bottom drain

[zimm]

I just took over care of a pool with the house we bought. The prior owner told me the pump doesn't have enough suction to run both the bottom drain and skimmer at the same time (there's a valve position for both... I think). She left it on skimmer unless leaving the house for a while or during a storm, in which case the bottom drain was selected to not worry about clogging the skimmer basket.

On day 1 of having the house, I tried it on "both" and the next day the pool was a cloudy, algae mess. I think it was just bad timing because the chlorine was zero. I shocked it back to life and now it's nice and clear. I'm just confused on what I should be pulling from for the filter.

 

[Richard320]

There's a good chance you had stagnant water in the drain line.

I just played with my diverter so I have some flow through the main drain - not much; there's just the slightest visible reduction of turbulence in the skimmer. That's enough to keep the water circulating down deep, so there isn't that temperature stratification you find in some pools.