This all makes a lot of sense. Thanks for the summary.
The Vertex diffusers are rated at .5cfm to 2cfm. If I was trying to run one of those with my compressor which puts out 4.5cfm that would probably be what caused my pressure at the pump to go up.
Sounds like you are on the right track to me. One diffuser = need to bleed some air off. Two diffusers will be about perfect. Remember, your pump will put out somewhat less CFM against a 12' static water pressure (6 psi) than it will open flow. So you might have only 3.5 or 4 cfm at 6 psi.
Like I said before, I'm no expert. I have run pond aeration for a total of two or three weeks last fall as a temporary experiment in preparation for installing a permanent system later this spring (soon I hope). My knowledge is mostly from reading a bunch (here on PBF as well as mfg spcs) last year in preparation for installing a system myself. But I have had many years with pressure and flow rates in hydraulics and air so have what I feel is a very good layman's working knowledge on flows and pressures. I'm also a scuba diver and understand static water pressures at depth. So that is the background I speak from. Definitely not from years of experience with pond aeration systems.
With the above in mind I will give an opinion (that very may well be wrong because of lack of experience, but it is worth every penny you paid for it
)
My opinion would be, where you have had a fish kill, you want to clean up some muck, where you are in "remediation" mode, my OPINION would be you could use all the air you could get. You might stir the pond up and make it turbid with old muck. So what? Nutrients stirred up should give you a good algae bloom. It might make your water look "yucky" for a while, but the added disturbance should get you the quickest results of remediation.
After all what does the air do? It moves water. The bubbles don't do much themselves except move water. The bubbles are inducing current to move water. I don't see any way (and I have been wrong before, many times, so it is an opinion, not expert advice) that you could produce too large of current in the water to hurt the current fish population or do any permanent damage. If you don't like the results being obtained, do something different.
If it were me, I'd go for it. Move some water with all the air you got.
