with warm water in your cylinder helps you expand faster and for
some reason keeps your cock fresher so you don't have to take breaks
as often. Also, the water pressure counteracts suction, so you get
the same displacement (and therefore expansion) with less suction
on your dick. Hope that makes sense - anyway, it means you have
less of a problem managing the pressure.
trick with water pumping is to avoid accidentally drawing water
into your pump. Be sure the hose is above the water line before
by warming your tube in hot water for a few minutes. Then fill your
cylinder 1/3 to 1/2 with warm water - as warm as your cock finds
comfortable - too hot and you'll get a water blister on your cockhead.
How much water you use depends on how big you'll get in the set.
you expand, you may need to drain off some water to maintain an
air space so you can keep pulling. To drain off you can squeeze
a finger into the cylinder at the base.
you pump with water you'll find that you don't need to lube your
cock (except for milking) and you may not need lube to get a good
seal. I don't use lube myself. Sometimes bubbles rise in a stream
but I find this tickles!
best water pump of all is to do it in a hot-tub.