For feeding and emptying larger amounts I used a couple of micro jet (Mj450) pumps, they're old and well used on/off up to 7 times a day for years and still going.
MICRO JET 320 OXY WATER PUMP ( MC 320 OXY ). · This is the Micro Jet 320 Oxy Water Pump (MC320 OXY). MICRO JET 450 OXY WATER PUMP. · Max flow: 320 l/hr @ zero height.
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Typically they're 1/3rd the price in the US.
They draw from the bottom of the pump leaving only a few mm of water/nutrient in the bottom of the saucer/bucket whatever.