Dissolved oxygen problems?

[Aguywithfeet]

Made a sand filter for a soon to be fish pond, for now its still an above ground pool. I am using the old pump for the pool. It seems to be working ok but I keep getting bubbles in the line going to the pump, which eventually cause an air bubble to make it stop working. any  ideas how to solve this? I can only think of some sort of bleed valve or a sump, either would have to be automatic. I think the root of the problem is a filter that filters to slow or a pump that pumps too fast. This is the lowest rate I want to be pumping at. This first post so take it ready on me please

[Watt]

Hello and Welcome.

I sorta doubt the problem to be cavitation from the pump.  My guess with out a diagram or picture is you have air getting to the pump.  What happens when you turn the system off, do you get a drip in the line to the pump?  This is a assuming the pump is below water level. 

[damian]

Is your filter by chance between the pond and the pump on the intake side of the pump?  In other words, does water flow from the pond, through the filter, to the pump and then back to the pond?  If so I urge you to move the filter to the discharge side of the pump.  Whatever you are filtering out will harm the pump less than the cavitation that you will get if your filter restriction causes a low enough pressure in your pump suction line to pull in air through little leaks that you can't even see.