Thanks for the tip Axer, I checked the delivery head on my pump (Hydor L20), i'ts 135 cm. It's 66 cm from the base to the VGA, so it should reach, if it's not powerful enough I'll buy a new pump, maybe an Eheim. I'm trying to keep the cost of this whole project down and the Hydor pump is one that I have lying around. The whole frame is made from scrap metal I pulled out of a skip

One man's rubbish is another man's treasure!