Submersible Well Pump Upgrade!

[iqinvinc]

Hello,
I ordered 1&1/2 Hp Goulds Jet hooked up with 2-5000g tanks and works great! Great price too!
I have older well (20yrs) thats 12” casing. water at 320ft, pump at 420ft.
Current Subm pump is 8-10 yrs old and only producing 1gpm I have pump saver hooked up and it runs 24/7. filling tank about 1200g per day. seems like something clogged up in the pump filter or someth. previous owner saying 7gpm-1 & 1/2 hp pump is down there, but wasn’t sure. but he never had problem with well drying up for 10 yrs, but of course he only used water for 4 bedroom house and no trees. now I have 1000 fruit trees with irrigation system soon to be using about 3000-5000 gal a day. my pump just can’t keep up. pump saver flashing and pumping water 24/7, looks like there is enough water in the well but only pump out so little,
Q1. What could be the problem? age of pump? or mineral built up?

I should eventually change to new pump, I asked local well guy and he would change pump even if I supply my own pump in order to save some money. So, I ask your expert advise to select right pump for my need.
I would like to pre order the pump before we pull the well pipe if possible, so I won’t have any gap watering my trees..
Q2. I’m looking at Goulds 13gpm 3hp for my 420ft well, would this fit my application?

it seems like big jump without knowing true capacity of water in the well.
hope pump saver does the job if there is not enough water.

Q3. what would be the disadvantage using high gpm/hp (13gpm-3hp) pump VS. low gpm/hp(7gpm-1&1/2 hp) IF there is not enought water in the well?
Please help! Thank you in advance.

[dlamp67]

Q1 - The existing pump could just be wore out, running 24/7.

Q2 - I can't answer this question without a little more information. Please see below.

Q3 - The main difference will be the performance of your well. If you put a higher volume pump in the well, but, the well can't produce enough water to keep up with the pump, then you will have issues of the pump breaking suction, thereby, potentially locking up the pump.

It would be best if you can give me more details about the application. 1 - How far is it from the top of the well to the storage tanks? 2 - What size pipe are using from the well to the tanks.

[iqinvinc]

Top of the well to storage tank is located about 300ft long and 40ft H elevation. 1" pipe down to the subm pump, 1&1/4" pipe from top of well to the storage tank. Thank you so much for your help!

[dlamp67]

The 10GS15 would get you about 11.5 gallons per minute at 400 total dynamic head. This calculation would be based on your 320 foot water level and your 40 foot elevation to the tanks. I am sure you will have draw down in the well as the pump is working, therefore, you would get around 9.5 GPM at 450' TDH or around 10.5 GPM at 425' TDH.