Please help. The bell siphon in our aquaponics setup has a mind of its own. Sometimes it will work fine, then, with no changes will stop firing and just trickle water out of the stand pipe. I've tried adjusting the speed of the pump and fiddled with different size pipes to cover the stand pipe. When I change the size of the cover pipe, MAGIC, it works again. Then, I'll check 30 minutes later, not working. If I reach in the media excluder and slightly move the cover pipe when it's overflowing, presto the siphon fires. What am I missing here?