osmolator pump alternatives?

[Willito]

How far up are you going. I have no problem going vertical 6 feet and 6 horizontal. You might want to check for trapped bubbles in the pump. Also if your pump happens to run dry or in low water for any period of time, it too will trap bubbles and may not run properly even after you refill the reservoir. Try banging the pump against the bucket to release the bubbles and it should resume normal. Best way to avoid this is to never let the water level get too low in the reservoir

Suggestion, especially if your pump is working against such gravity force, is to install a check valve. This will ensure that the back flow won't create bubble pockets in the line and will also prevent flooding. How this helps.