There are benefits to both brands of compressors. The Hiblow 5.14ft suggestion operation comes from their website where their optimum operation pressure is 2.57psi (yellow dotted line on their pressure curve chart for HP100&HP120) and from the Hiblow operational suggestion to a Hiblow user.
HiBlow does have lower electrical operational costs plus they run with less noise than a rotary vane. Main differences are company suggested operational pressures. Most all air compressors create less air flow(CFM) as the head pressure(depth) increases. Manufacturer air flow charts show these outputs.
Gast 0523 can operate at 10psi and suggested operation is 10psi or less which works great in ponds deeper than 6-8ft up to 18ft deep. Your quoted info about - "The Gast pump puts out 10-15psi, that's a lot for a diffuser, so people add a regulator, to bring the pressure down. It wastes money to to do work that's not needed", is misleading.
The Gast 0523 can create but does not put out 10-15psi unless pond diffuser depth requires that amount of pressure(psi). This can be measured with pressure gauge. The Gast rotary will only create a psi that is needed due to the amount of air release resistance or pond depth (head pressure). So at X ft deep the 0523 unit only creates X amount of psi where operational amps are also proportionally lower (example 8ft=4psi); no psi waste nor need for a regulator. Do not confuse PSI with CFM. Your operational cost estimate numbers for the Gast are also biased toward the higher $$ depending on the numbers used. More air flow can mean the pump does not need to run 24/7 to produce the same water flow compared to one with less cfm air flow. Over aerating can be similar to the benefits of hyperventilating.
Pushing the Hiblow deeper than 5.5ft adds additional psi stress on the unit; manufacture's opinion and also mine. Deeper than 5.14ft also reduces the CFM, the pump does both, just with added mechanical stress. Running the Gast 0523 deeper than 18ft puts added mechanical stress on the 0523. It can do it but just with more stress similar to that of the Hiblow. Which compressor is best for a pond depends on the needs of the user. Both brands have benefits - pros and cons.
Last edited by Bill Cody; 03/28/21 09:38 PM.
