Glass heaters should be just fine.
Options to consider
GPD - Gallons per day - Quite often the larger output membranes don't purify the water as well, so as appealing as 100 GPD sounds, make sure the membrane is high quality. You will never actually get as many gallons per day as the membrane is rated for, so round up your need.
rejection rate - high rejection rate produces very pure water, with more waste water. Low rejection rate produces less pure water, with less waste.
Number of stages - Minimally you want a carbon stage, an RO
stage, and a DI
stage. Other options include extra carbon or DI
stages, or a prefilter stage. If you think your water is hard, a prefilter or two stages of carbon might be a good idea. The fine pore carbon can get clogged up pretty easily under some water conditions. Generally more stages is better, but I'm not personally fond of the double-di
faucet/pressure tank (option)- if you want to use the RO
for family purposes as well, you may want to install it under the kitchen sink with a pressure tank and faucet. This will reduce the GPD output, but you will have a couple gallons handy at all times for drinking and topoffs.
float valve/holding tank (option) - if you only want RO
for aquarium purposes, get a large trash can and a float valve. The water will fill the trash can until the float valve is triggered, and shuts off the water.
meter - this will help you keep tabs on the performance of your filter. Testing before the filter, between RO
, and after DI
can give you a real good idea of when you need to change the RO
stages. You may be able to save money on filter changes this way, as well as see tangible results of your filtering. The carbon stage should be changed out on the manufacturer's schedule, as too much chlorene can damage the RO
There are a bunch of e-bay stores with good deals on RO
units. I'd start shopping there.