Troubleshooting catchment pump "hiccup"

[rrlovesbi]

Finally replaced our 10K gallon doughboy catchment with a new 10K tank and "food grade" liner last month. A month prior ran a new 1.25in feed line from water tank to a new 1Hp Everbuilt pump.  System was working well with new tank half full. Noticed that with full tank the pump now hiccups for less than a second when it starts up. Even if I just turn on a sink faucet slightly, and pressure tank drops below 30.  Pump motor does not stop, it sounds like it struggles for a moment, which was not the case before. 

Not sure if the water pressure from the full catchment tank is causing the hiccup? There is a backflow preventer installed in the feed line. The output, from the pump, feeds to a branched T line. One side to pressure tank and other side direct to house (filters and UV).  The combination of the 1Hp pump and 1.25in feed line gives us enough water flow for 3 simultaneous showers to run on first and second floors. This is great, but want to make sure there is not a problem in the system. 

Would appreciate any suggestions on what this might be or further troubleshooting.

Mahalo
Rob

[terracore]

I don't know if the water level in the tank would make a difference unless it was uphill from you, or you have a floating intake.

1) You should have a valve in the line coming out of the pump and another where it goes into the pressure tank. Are both valves open?

2) Does the pressure tank have enough air in it?

[rrlovesbi]

I don't know if the water level in the tank would make a difference unless it was uphill from you, or you have a floating intake.

1) You should have a valve in the line coming out of the pump and another where it goes into the pressure tank.  Are both valves open?

2)  Does the pressure tank have enough air in it?

Nope, not uphill - about same level as house pad. Intake near bottom, both valves open. Checked pressure in tank without water in pipes.