Compost tea soil injector

I'm not familiar with the compost injection equipment, although my husband made a venturi type bubbler for our aquarium that works on a similar principle. It looks to me like you have a 1/2 inch T side piece rather than a 1/4 inch side piece. This may mean that the hose water will find it just as easy to go down there as straight across to the injector pipe. I think this side pipe does need to be smaller in diameter to produce the pressure difference that will suck up rather than blow down.
I think you have a compression joint to the compost tap, so maybe it would be possible to add a constriction between there and the T-piece without having to start again. - I'm thinking some flexible thick hose pipe material could be pushed inside to reduce the diameter and that would be enough to see whether it might help.
Sorry - lots of thinking and not much certainty for you, but it may be worth a try.

Bryant RedHawk wrote:It looks like there is to much space between the water line and the siphon tube inlet.

How much space should there be between the garden hose line and the siphon tube inlet?