I just made the upgrade from 2500 @ 3G's to 2500-3000 @ 5.5G's .
nite & day !
1st, I read all the PWr wash boards I could find.
Almost all city water will give you 5GPM's, (here it's 10 - 12+).
You will begin to see probs when you go bigger, to the 8GPM machines, which become seriously expensive anyway.
GPM's is what you want.
Pressure, as you know, is dangerous. Can, and will, eat up wood AND concrete.
If low flow expected, a surge tank about 100G's is probably minimum.
I'm going to try 55G drum, because I've got one!
Well fed? May require the 235G - 300G tanks w/float valve & strainer.
If you run the pump dry it will cavitate and eat the pistons...
Also, big chance of sand from well fed sources. Will also eat the pump.
Seems it always gets complicated... Bigger pump, you'll want a tank, that means a trailer, more hose, wands, special tips... and chems!
thegrimescene.com is best source info available on pressure washing.
Read through their threads...
r