"Glenn Ashmore" wrote in
:

For an R/O system you want something with a sensitivity to reliably
know when you get below 200 ppm. Hanna makes a series of TDS meters
that you can find at many aquarium supply sites. The HI9833318 is a
$185 high range panel mount meter. With an HI7634-00 probe remote
sensor it has a range from 1 to 2,000 ppm. You can set the relay to
trip at any level and it is sensitive enough for R/O purposes and it
comes in 120VAC or 12VDC. I think the probe is 3/4 NPT so you will
probably have to add an adapter to your product line.

When I was building my system I found the older 983319 in an aquarium
supply site. Talked to the Hanna engineers who recommended the 120V
model over the 12V model because voltage fluctuations could cause
reading errors. The 983318 is the new model and even if they haven't
figured out the voltage errors it would be a simple matter to put a
$20 buck/boost regulator on the supply line.

Since I put up a picture of my panel on the web site I have seen
several of the pro systems add the same model.

BTW, for a really nice looking panel check out
http://www.frontpanelexpress.com/. High quality reasonably priced
professional looking custom aluminum panels and free software to
design it with. Delivery in 2 weeks or less.

Glen,

Thanks for the info. I'll check out the Hanna series.

I had book-marked the Front Panel Express site quite a while ago (probably
from a posting from you) and have been using their software to lay out the
panel. I was quite amazed at the low cost. I just need to fill in a few
more components such as the TDS display.

-- Geoff
www.GeoffSchultz.org