Go to the hardware store and ask for a pressure gauge that screws on a hose bib and see what your incoming water pressure (psi or pounds per square inch) is.
Next, run your RO/DI and using a measuring cup and watch or clock measure the waste water flow for exactly one minute then do the same with your treated water flow. Optimally this should be about 4:1 or 4 times as much waste as treated.
What are the results of both of the above?
While warmer water does make RO/DI faster it is not smart to war the water as the energy it requires to heat a bucket of water with a coil of plastic tubing in it is prohibitive. The BTU's an aquarium heater produces will not do it, sounds good but doesn't work that way. Look up how many BTU's are required to raise even one gallon of water one degree and you will see what I am talking about. Besides that plastic tubing is a horrible conductor of heat and cold so the heat in the bucket does not exchange with the cold in the tubing efficiently. 77 degrees F is not the ideal temperature to make RO water, it is just a number the membrane industry has chosen as a standard for all manufacturers to compare products against each other. The truth is colder water treats better since it is more dense, less viscous, and gives you lower RO only TDS so DI lasts longer.When you warm the incoming water your membrane is less efficient since the water is more fluid and more passes through the membrane carrying the TDS with it which is what you don't want.
Get your water pressure and your waste ratio and lets go from there before you spend money on boosters or anything else. You may only need to fine tunr your waste ratio with an adjustable flow restrictor at $5-$6.
