Originally Posted by Ric
There are Fountain pumps and there are transfer pump. Fountain Pumps will produce more pressure and less volume. The Manufacture should have pressure and spray height data on their website. Along with nozzles and light kits etc
My main point being, it is the type of pump that is the important factor. Only other thing I can tell you is Trail & Error on the pumps you are now using.
All that I have found is what they call "feet of head pressure" which is listed under the various nozzle types to determine height of spray/plume or height and throw. Someone has to know how to convert this to PSI.