low water pressure

[retire2$]

With the shower on the flow of the water from the shower will drop to a trickle when the outside faucet is turned on. This never happened before until I replaced my old storage tank with a new one. Both tanks were Well-Mate WM6 models. I took some measurements and they are as follows:

1. The pressure switch is a 30/50. The cut in pressure reading on the pressure gauge is 25 psi.

2. Shutting off the power to the pump and opening a faucet until no more water comes out of the faucet the pressure tank has a reading of 23 psi at the shrader valve.

3. Turning on the power to the pump and closing the faucet the pressure switch will cut out at 50 psi. Pressure at storage tank shrader valve is 43 psi when the pressure switch cuts out at 50 psi.

4. Opening a faucet and collecting the water until the pressure switch cuts in is approximately 5.5 gallons. The spec sheet for the Well Mate indicates the draw down for this model is 5.9 gallons.

5. When a faucet is open the pressure gage drops to 25 psi and then momentarily drops to 0 (maybe 1 or 2 seconds) before the gauge goes back up to 25 psi and then starts to rise as water is added to the storeage tank from the well.

I have a submergible pump. Any suggestions is greatly appreciated. Thanks in advance for any replies.

[agmantoo]

One of the 2 devices that you are using to measure the pressure is inaccurate. You have too much air pressure in the Wellmate! Let the air out by 2 lbs drop until the problem ceases. This is the problem, been there done this one a number of times.

[raymilosh]

i think you have 2 separate issues. Having the pressure momentarily drop to zero is one of them and can be fixed as agman says. I'm thinking the other problem of the low pressure problem in the shower is due to some blockage right inside the showerhead...it probably got there when some garbage got in the line during the changing of the pressure tank.
the shower prolly works ok when the whole system is pressurized and it's the only thing running, but when any other device is turned on that has less resistance to water flow, the water goes that way preferentially.
you can test the idea by starting the shower then turning on the hot and cold in the bathroom sink and see if the same loss in pressure happens