Ric, Your right on with the voltages they can all be a problem in the right conditions. Now back to the original post "Cost efficiency"Yes higher voltages run for less $$$ and between 110 and 220 there is little difference. This is always a common question when I size a system for a customer.A 1/4 HP motor (Gast 0523 r vane pump)at .07 cents per KW costs >26 cents to operate for 8 hours on 220 volt and .28 cents per 8 hr on 110 volt. A 1HP system (1423 Gast) costs .86 cents 220 volt and .91 cents 110 volt for the same 8 hour period.So cost difference is there but not great.Obviously as you move into the larger HP fountains the cost spread is greater but usually 110 volt is not an option on larger fountains.WE wont get into slower RPM motors when cycles are changed from 60 to 50 (another can of worms)When speaking of aeration "EFFICIENCY" I find the most overlooked area is in the choice of diffuser.If you are pumping 1.5 CFM of air for example to one diffuser you may want a diffuser that turns over the most amount of water. In 12 feet of water a good turnover rate would be 2600-2800 GPM. No airstones that I know do this and only one membrane manufacturer.Most rubber membranes are made for the wastwater industry and are designed for large volumes of high CFM of air.So when you mention "EFFICIENCY" consider looking at diffusers that have been tested for water turnover (let the testing method debate begin)For some turnover testing rates of different systems check out the info at vertexwaterfeatures.com (had to get that plug in)All good posts, Ted "ForeverGreen"
