chloramine...

[HighSeas]

I just did some research on RO systems tonight. Still a work in progress...but the Watts units remove Chloramine (amongst other things) and get very good reviews. I need one because I have a water softener and my orchids don't much like that.

[Ray]

OK, this is advertising, but before you commit to an RO system, send me an email. I sell them at much better prices than most (& include 2 years worth of consumables, tools, etc.), and can custom-build them to meet your needs.

For example, I just completed one for a customer that just moved to an area where there is particularly silty water. Watts had recommended a standard 4-stage system, but we configured that system to include 20-, then 5-micron sediment filters, a carbon filter before the 100 gpd membrane, and has a reduced flush water output, improving the efficiency to 2:1, rather than the standard 3- or 4:1.


Ray Barkalow
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[Discus]

Originally Posted by HighSeas

I need one because I have a water softener and my orchids don't much like that.

You should probably get a plumber to help you install the RO before the softener in your household system (unless you're happy doing plumbing). You might like to install a pipe to somewhere in your garden that takes the "waste" water and keeps plants that like more moisture irrigated.

[DavidCampen]

Especially with softened water as input, there is no need to have a 4:1 or 3:1 ratio of reject water to produced RO water like the typical household units have. I run at a ratio of 1.5:1 using non-softened water with 200 ppm TDS as input and the RO membranes have not shown any reduction in ouput after 2 years of use. I am thinking of adding an additional RO membrane in series with the 2 that I already have to increase my production rate and doing that will bring my reject to product ratio down to 1:1.

[Ray]

So David, when you state "in series", am I correct to take it that the flush water from one is the input for the next?

[DavidCampen]

Originally Posted by Ray

So David, when you state "in series", am I correct to take it that the flush water from one is the input for the next?

Yes, with a single flow restrictor after the last membrane in the series, so you could think of it as one long membrane. This of course means that the flow velocity along the face of the membrane(s) decreases as you move from inlet to final outlet and maintaining a significant flow velocity is important to prevent fouling of the membrane. The advantage though of having 3 membranes in series instead of one long membrane is that if any membrane fouls it will likely be the third one in the series which can then be replaced independently of the other 2 membranes in the series. I use Dow Filmtec residential membranes.