Bell siphon construction - part 4 tuning

So getting this thing to siphon correctly is a bit of a challenge.  First I will start with what the water looks like at different stages.  This is the normal water flow.  It is coming out of the drain hole in the side of the stand pipe.  This was put there in case power is lost.  However it will look like this as the top of the stand pipe starts feeding water.


As the water starts to build velocity and suction it will look like the picture below.  If it stays like this you will need to increase water flow into the grow bed.


When proper water pressure/suction has been achieved it will look like below.


Once the grow bed has drained the siphon bell make a "straw sucking" sound.  Then the end of the drain pipe will make a "burping" sound.   At this point suction should be broken and the cycle starts again.   If the drain pipe does not burp and water continues to flow out you need to decrease water flow into the bed.  It may take a few hours to get it right.

Some tips on increasing suction.  First increase the length of the first down tube.  Mine now sits at 6 1/2".  The other two pieces of PVC come in at 2".  This has created a reliable siphon.  You may have to adjust the down tube or the other tubes to make it create siphon.  Also the water flow will have to be adjusted.  Temperature and bio-slim will be two other factors to deal with.