Ook wrote:
S

Are you sure it's bladder elasticity, and not air pressure behind the
bladder, that is giving you pressure? A bladder can't hold pressure - it
would burst. Bladder tanks rely on the air behind the bladder, not the
elasticity of the bladder, to maintain pressure when the pump is off.

I irrigate a 1/3 acre garden and yard with a small pump. The problem with
1/2 horse pumps, especially the cheap ones, is that one day you decide that
drip irrigation won't work for some odd patch of garden, and you go and hook
up a couple of impact sprinklers. That is when you find that your 10GPM pump
only pumps 10GPM at ideal conditions that don't exist in the real world. And
having been through several different 1/2 horse pumps, I can testify that
they are not all equal. My Gould JRS5 is an excellent pump. I also have an
el-cheapo Flowtec that I got from Home Depot that is a worthless piece of
junk. Today, I use a Star 3/4 horse pump. I don't need the theoritical
volume it can pump, but the difference between the smaller pump and the
bigger pump is that it takes 30 seconds for the big pump to fill the tank
and bring the system up to pressure, where the 1/2 horse pump took a couple
of minutes. Also, the Star maintains volume at 55psi, where most cheap 1/2
horse pumps barely trickle at higher pressures. You put them under load, and
the small pump runs constantly, and the big pump cycles at a comfortable
rate.

/soapbox

Your soap box may have just talked me up to the 3/4. Granted I'll be
using it to water stuff for the most part, but there will be a need to
do more from time to time.

At the very least I'll check elsewhere for a pump than at Lowes.

Oh, and some pressure tanks that use a diaphragm are indeed
pre-pressurized from the factory to specs. They don't have any way
however to re charge the tank and fill the other end with air.