Water does come out of the pickup behind the prop and you could cover it if you wanted to for a more direct flow. I’ve never worried about it too much because there’s still enough pressure from the garden hose, even with the faucet open 1/2 way, to force water up past the impeller to the powerhead. Of course this doesn’t really test the impeller but it still is a good way to test initial running, settings, etc. when you don’t want to use a bucket or like you said Buc, when you have stand limitations or a heavy motor like yours.
