"Boomer" wrote in message ...
I do not know what you mean by cycle. A booster pump should keep a constant pressure on
the RO membrane. Cycling would be self-defeating, for if the pressure changes, do to a
on-off phase, there would be a continuous pressure difference on the membrane.

Or are you talking about a RO container pressure pump, that keeps made RO water in a
container at x pressure to pump to y place.

OK, more details...
I have got Aquatec DDP5800, what they call "a demand/delivery pump".
Hooked it up to my KENT 10gpd barebone RO system and turned the pump on.
There was a pressure gauge in between the pump and the prefilters...

When the pump was cycling on and off on the limit switch I saw the gauge
going from the 40PSI (my tap water static pressure) to 65-70 PSI the moment
the pump was on. 1/4, maybe 1/8 of the second later the pump turned off itself on
the pressure switch and the pressure started decreasing to the 40PSI when the
pump turned itself on again... This cycling seem to be due to the fact the pump
had large capacity and pumped pressure high up really quick reaching the limit.
The water did not have the way to escape through the RO filter that quickly so
the pump turned off. When the pressure relatively slowly dropped back to the
40PSI the pump turned itself back again...

I almost feel like I need a "water capacitor", using kind of electrical analogy...
Some flexible device/container which could take the pressure from the pump
and release it over time feeding the need for water of the RO filter... Or a much
smaller capacity pump which will just barely keep up with RO filter demand.