Well Pump and Pressure Tank

Your site helped me repair my old well pump & pressure tank back in 2007 (very large tank is bladderless and had become swamped over time; pump is Sears 1/2 hp 20/40). I drained the tank, added a pressure valve and schraeder valve, then pressurized the tank to about 27lbs (the pressure switch actually starts the pump @ 25lbs and stops it at 60lbs). The solution worked perfectly and I had pretty solid water pressure.
Last week I noticed the water pressure was beginning to seriously dwindle and that the pump was starting to run more often...at times when there wasn't any water being used. So, I recalled the advice I received regarding the need to add some air pressure every now and then if the water pressure dropped (it had been about 6 months since the last time I added any air) and attempted to add some.
When I began to add air into the Schraeder valve, I noticed some water back pressure, which pretty much confirmed my suspicion about the tank being swamped (the schraeder valve is about 3/4 the way up the tank). So I proceeded to add air pressure in an effort to force the water level back down the tank...but I think I added way too much air pressure because the water pressure continued to drop in the house (shower pretty much only drizzled now...even when the pump was running).
So I let some air back out of the tank and sure enough, the water pressure rose. I opened the outside hose spigot and allowed the tank to drain and repressurize (by the well pump) several times to normalize pressure, then checked to be sure there was no water coming out of the schraeder valve. There was a little, so I added a little more air.
The water pressure in the house seemed to be more solid, but seems to drop noticably as the pressure tank pressure drops (from water being emptied, but before pump starts). It gets pretty dismal between 35lbs and 25lbs when the pump starts, then the water pressure in the house goes back up as the pump runs. I'd like to have solid water pressure in the house all the way down until the pump starts.
What do I need to do? Should I adjust the pressure switch to start at 35lbs instead of 25lbs (I recall there are two screws in the pressure switch that control pressure range and shifts entire pressure range up or down...but to be cateful when adjusting due to shock hazard)? Do I still have an air pressure situation? If so, do I need to completely drain the tank again then refill with a baseline pressure (like I did when I installed the pressure guage & schraeder valve), or should I just add or remove more air?
This site has always been of great help to this city dweller who now owns a farm in the country. I await your sage guidance. Thanks, Mark.

You can't push the water level down in a tank unless you open a faucet somewhere which is how you dewaterlog a tank with a compressor. Push all the water out. When the faucet spits air, close it and then keep adding air until you have around 20 psi. Then turn the pump back on and your pump should cycle far less.

It wouldn't hurt to have your switch set at 40 60.

bob...

Thanks for the advice. I emptied the tank completely of air & water (there's a drain spigot attached to the bottom of the pressure tank and I attached a hose, opened the spigot, allowed it to drain until it was spitting air and air pressure guage went to zero, then removed the schraeder valve and guage and nothing more came out). I then closed the spigot, removed the hose and reinstalled the pressure guage & schraeder valve. I verified start & stop pressure points before I started and the pump kicks on at 30lbs and off at 55lbs. I'd like to adjust the on/off pressures to 40/60 like you suggested. Any idea which of the two screws on the pressure switch adjusts which? Also, how much air should I charge the tank with before turning the pump back on?

If your going to set your switch to 40/60 I would put around 30 psi in the tank. That should let the air stay in the tank when the pump comes down to 40 psi.


bob...