Ok I got some data tonight. 12 1/2 psi with the dissuser @ 7 foot. Max depth of pond is 8 that I found. Pulled the diffuser ring off and with the line on the surface it was 11 1/2 psi. Didn't bother sinking it. I cut the line @300 foot where some tree roots was pushing it to the top. 8 1/2 psi.
It will take me some time to replace the air line but I can replace the diffuser in an evening.
Esshup, I have been buying my feed through you this year along with a few things i need you have. I see you sell vertex. You have my business. If you have a diffuser that will work let me know. I can't post pictures but I will try to email you some for more information.
My pump specs are 4.6 cfm max psi 40
Thanks