It's impossible to say if this system is overkill without the lift rate data that Highflyer mentions and most aeration vendors don't give it out or know it to begin with (To be fair, liftrates are difficult to measure and/or calculate). Vertex is a common name with PB board members and they supply lift rates for their diffusers...I use their diffusers. If the kit heads lift much less water than the Vertex heads then the kit heads need more air to do the same work, hence a larger pump. My 3 head system uses a 1/4 HP rotary vane pump (Gast 0523).

6 CFM would be a lot of air to push through two Vertex diffusers, but I can't say for the one's in this kit. I keep my air flow about 1 to 1-1/2 CFM per diffuser. IF, for say, the kit diffusers have large holes and plenty of them...they will move less water than one with smaller holes. The smaller the bubbles (given the same CFM), the more water lift you get and the more turbulence at the surface...the more aeration you get.

Air control valves would be used to balance the flow going to each diffuser. For example, with one head in deep water and the other in shallower water (without any air control valves)...the
shallow head would get the most air and be more turbulent. The air would be taking the path of least resistance. The deeper the head, the more pressure required to push the air down to that depth. Use 1/2 psi per foot of water column as a good rule of thumb...a head in 16 foot of water would require 8 psi (1/2 psi X 16 feet) of back pressure to produce bubbles. A head in 8 foot of water would need 4 psi...more air flow will come out of the shallower head. So, you put a valve on the shallow line and choke it back some which drives more air to the deeper one equalizing the water boil/lift. This is not an absolute necessary, but you be glad you put them in. I like to balance the boils so that all of the boils are about the same. Too much air through a single head could be "blowing it up" (equals shorter life).

My system typically runs with about 5-7 psi at the pump outlet, so, I use an adjustable relief valve that I set to about 11 psi. If one of the lines get pinched, clogged, or filled with water that can't be pushed out...the relief valve pops open and relieves the pumps pressure to the atmosphere. This can save the pump from deadheading and burning up. 50 psi is unnecessarily high for your application. If you were pumping air down to 90 feet deep (90 feet X 1/2 psi per foot = 45 psi), a 50 psi relief valve would make more sense. With that said, I am not too familiar with piston pumps and it might not be a big deal, but It seems too high for my comfort level.

Rocking piston pumps are common for aeration systems especially for deeper ponds. Some septic air pumps are diaphragm pumps and those are not so good at pumping air down deep. The rotary vanes fall in the middle somewhere. The deeper the pond, the more pressure the pump must make to maintain good airflow. And, all pumps lose CFM the deeper the head is set...some are just better at maintaining air flow (CFM's) in deeper waters/higher pressures. Piston pumps are the best for deeper waters.

I pieced my system together using the Gast 0523 rotary vane pump, 3 Vertex 9" diffusers and a bunch of plumbing I scrounged up. It was not much of a cost savings compared to a Vertex Kit, but I enjoyed the process more than the potential savings.

By looking at just the specs and assuming someone with some background in aeration designed it, I think this system would be a good fit to your pond with a diffuser in each end. I would consider doing two in each end as this pump sure puts out alot of air and you get better surface agitation hence better surface aesthetics. You want the system to be over sized to some degree because you live in a warm climate and will not be running the air during the day much in the summer. Daytime summer heat can really get the pond hot with the air running. I run mine only at night during the summer. So, it's got to do the job in half the time (12 hours at night).

I'll try to find some threads worth reading and post the links back to this thread. You can get pretty deep into the theory of system design in a hurry.

Fish on!,
Noel