Reverse Osmosis Systems
 

I'm looking for information/recommendations for a single-faucet RO system for watering a collection that could possibly expand to 80-100 orchid plants. There are a gazillion systems out there and it would be helpful to know important options to look for. Thanks.

Try this website: Systems

This one may be overkill, but it's reasonably priced, efficient, and has plenty of capacity for you to expand. I have been using it for nearly a year and a half.
GrowoniX GX150-HR - 150 GPD Reverse Osmosis Filtration System

Thanks, Roberta. I'll add this one to the info page I've started. It looks very similar to one that I saw in a You Tube video. Permanent mount? I've also noticed that there are small portable systems that you can hook up to your faucet, filter the water you want, unhook the unit and stow it until next time.

This one is a permanent mount. One could mount to a plywood board for portability - frame just fits over two properly-placed screws. The other things that would be needed would be a container to run the RO water into (trash can works fine)and a pump to put the water where you want it. (submersible pumps are quite inexpensive) Effluent can either be captured or put down the drain. I run mine pretty hard - in summer, utilize as much as 40 gallons RO water a day, which would then produce about 80 gallons of effluent. I capture the effluent and pump it onto the front lawn (But then, my city water isn't all that bad, ranging from 200-350 ppm TDS on most days, so increasing the TDS by 50% it's still fine for plants that grow in the soil. )If you make less RO, wasting the effluent is less troubling

Thank you again, Roberta. Very nice of you to provide these details. It's always fun to learn new stuff.

I have used RO for about 30 years, and built, sold, and resold systems for 20+.

The first thing to recognize is that an RO system is NOT an on-demand water supply. You will need to store pure water for use and let the RO system refill it at its own pace. "100 gallons per day" sounds like a lot, but recognize that it is only about a cup a minute, and it would take a long time to water even a small collection at that rate.

Secondly, systems- actually the membranes themselves - are rated with incoming water at 65 psi and 77F. Lower pressure and lower temperature means the output is reduced. 10 psi and 10 degrees lower results in about a 1/3 reduction in output - more reason to focus on storage capacity.

If your water supply is chlorinated, you should opt for a 5-stage system to protect the life of the membrane.

A standard residential system is a 4:1 system; 4 gallons of incoming water will produce 1 gallon of pure, with the three remaining gallons used to flush the rejected dissolved solids away. Folks use the flush water for less sensitive plants, let it spill on the greenhouse floor for humidity, or as I did, to refill a pond for the local fauna in my neighborhood.

There are 3:1 and 2:1 systems available, but I recommend going no lower than the former, as the membrane can foul too quickly.

If you would like, I'd be happy to discuss this in more detail on the phone, and answer any question that come up. No obligations one way or another. PM me and we can set something up.

you can buy hydrologic micro 75 it cost only 129 dollar at there web site
micRO-75™ Reverse Osmosis Filter | HydroLogic Systems

That is actually a great little system, but a significant drawback (to me) is the fact that the carbon/KDF filter is proprietary, so you're stuck ordering from them.

I see they are $29.95 and good for 1000 gallons of flow (about 333 gallons of pure water), when standard filters are under $5 (I used to sell 2 for $5) with double that capacity.

I have extensive knowledge in aquaria. RO vs DI is still a big debate in that field. Is it still a debate in horticulture. I'm part of the DI camp and there are 2 main reasons why. RO systems to get pure water still require DI cartridges on the back end. No 2 is that RO systems waste more water than they make. Environmently with water shortages happening all over the world,I think DI is a better choice.