The AquaAir system is from AquaMaster and is an excellent commercial grade aeration system. While the issue is not the existing alternating current AquaAir system but, as I understand, your desire for a DC pump to operate your aeration system using an existing solar array instead of the 115 volt power off the grid, I would mention that this electric system might be a bit oversized for this shallow pond with a maximum depth of 5 feet.
The airflow of the AC pump is high, 4.8 CFM, and this is beneficial but the pressure operating capacity of this piston compressor system in the Aquamaster unit is designed mainly for deeper ponds with depths over 12 feet and can actually aerate deep ponds and lakes over 25 feet deep so the system in a shallow wetland or water feature that is 80 or 90 feet long by 50 to 60 wide at the most may not be the best approach especially as it only uses two diffusers.
An option in a shallow wetland or pond is a diaphragm air pump or even a regenrative blower sized accordingly which could offer the ability to introduce more diffusers and target the entry points of fine bubbles in more areas to create a more homogonous circulating and oxygen transfer due to a more efficient mixing.
As for a DC pump we do have some options but with small panels and the amperage output might not be adequate to achieve the same 4.8 CFM.
We did carry a commercial grade DC pump that offered 100 LPM output with an output of around 7 PSI which would have been acceptable as a replacement for your AC compressor but the amperage draw was fairly high unless you could swap to a 24 volt power supply with multiple batteries and a higher amp/hour capacity.
We do have a potential DC air pump:
DC 12 Volt 80 Watt DC Air Compressor
Flowrate vs Pressure - 1.6 CFM Open Flow - 1.5 CFM @ 4PSI - 1.3 CFM @ 6PSI - 1.1 CFM @ 8PSI
MAX 8 PSI ( +/- 16 feet ) 80 Watts Requires approx 8 AMPS for 8 PSI output
The airflow is less than half of your AquaAir compressor and while the 1.6 CFM of the DC pump is more than enough to provide air for two, three or even four silica airstones of 6 to 9 inches in length it is likely not enough airflow for the 12" diffusers that come standard with the AquaMaster aeration systems.
If you hadn't already added the electric system another option is to go with a solar direct system that uses a DC pump without batteries so it only works when sunlight hits the photo capture crystals on the panels. Strategically using multiple systems, like the DDKP2 which has 2 diffusers and 2 CFM output or the more commercial grade solar system DD3-352 which has 2.8 CFM output and two diffusers, around a large pond would provide more cubic feet per minute of airflow than the electric pump and would allow more diffusers to be placed in the pond.
The option of a turnkey solar aeration system with batteries, charge controller, diffusers similar to your AquaAir 2 system would be our PRSB2 which is priced around $7500 inclusive so would be in the ballpark as your electrical system but would have no additional costs associated with electrical draw.
In many cases an electric system can be used with small electric pumps with a low amp draw, much lower than the AquaAir 2 piston compressor draws. I'm not certain that retro-fitting the system with a charge controller, battery array and panels to ensure 24/7 operation would be cost effective compared to using solar direct units in which 3 could be purchased for under $5000 and give 6 CFM and 6 diffusers for placement around the wetland.
Any follow uyp questions let us know.