Sometimes it takes a bit to get a suction going. I syphoned it by mouth once and got great flow. I think I may install a squeeze bulb on the hose. Once it get flowing , it doesn't loose suction.

It was a used unit when we bought it. It's a 2010 model and had been used once on a cruise from Annapolis to Florida, then the boat sold and the new owner pulled the unit out. It had been pickled with pink anti-freeze and capped off.