Powering Grundfos A/C Pump in off-grid application

[inetdog]

I guarantee you cannot tell the water level in the well at 30' just by looking. There is no point of reference. I've been doing this for 20+ years and I can't do it accurately. I'll bet your level is deeper than you think.

You can often tell by looking as you lower a sounding weight and see it hit the water.
As long as the level is not hundreds of feet down, that is.

[cjb80]

I guarantee you cannot tell the water level in the well at 30' just by looking. There is no point of reference. I've been doing this for 20+ years and I can't do it accurately. I'll bet your level is deeper than you think.

OK, well I guess I can give you more information: I know that that's where the water comes in (i.e., the location of the perforations) per the well report and when they were drilling the well. This information combined with my visual inspection and the transition from dry to wet on the pipe that I extracted tells me where the water level is.

I agree that it is difficult to tell how far down it is by visual inspection alone. In fact it took me about a minute of staring into the darkness before I even realized what I was seeing.

[cjb80]

That inverter say 50/60 HZ. is it selectable? if it run on 50 cycle the pump performance will be cut significantly.

I am going to check on this the next time I am out at the site. Thanks for the suggestion.

Also, I am going to try and add a 10w light bulb to the circuit to see if that helps "wake up" the inverter from sleep mode. I will report on the results in about a week or so.

[MichaelK!]

OK, well I guess I can give you more information: I know that that's where the water comes in (i.e., the location of the perforations) per the well report and when they were drilling the well. This information combined with my visual inspection and the transition from dry to wet on the pipe that I extracted tells me where the water level is.
.

This is the third very, very dry year in California, and a historical report is not likely to be accurate for "right now" For my own well, the static water level was at -70 feet when the well was first drilled in 1980. In 2010 when the well pump failed and it needed replacement, the static level had dropped to -100 feet. My well's bore hole is supposed to cross three aquifers. I'm assuming they are located at -70, -100, and ~-180 feet. So, the upper most aquifer had totally dried. I monitor the well's pumping rate on a minute by minute basis, and what I see is that in wet years the well is putting out about 6.5 gallons per minute. Now, the well puts out about 5.5 gallons per minute at start-up till about the first hour. After that the pumping rate drops to 4.75 to 4.25 gallons per minute.

I interpret this as follows. In a wet year, the upper most aquifer (-70) is hydrated, and has a refresh rate of > than 6.5 gallons per minute. So, I can pump as long as I please with no drop in water level/pumping rate. Now, because of the drought, the uppermost aquifer is gone, and I start pumping from the second aquifer (-100), which has a refresh rate < 4.25 gallons per minute. As the water level drops towards -180 feet, the pumping rate drops, with the pump then stabilizing at a refresh rate of 4.25 gallons per minute, which appears sustainable.

I think that is what is happening in your well also. Your static level has dropped significantly lower that what it used to be, and drops even lower as water is pumped out because the static level is dropping.