Reef Central Online Community
The Filter Guys

Home Forum Here you can view your subscribed threads, work with private messages and edit your profile and preferences View New Posts View Today's Posts

Find other members Frequently Asked Questions Search Reefkeeping ...an online magazine for marine aquarists Support our sponsors and mention Reef Central

Go Back   Reef Central Online Community > General Interest Forums > Lighting, Filtration & Other Equipment
Register Blogs FAQ Calendar Mark Forums Read

Notices

User Tag List

Reply
Thread Tools
Old 02/12/2018, 11:43 AM   #1
km9830
Registered Member
 
Join Date: Feb 2018
Posts: 1
RO reject water ratio computation from TDS

I haven't see this information in these forums, so wanted to share.

The recommended brine to permeate ratio for RO membranes is 4:1. This is inconvenient to measure accurately in some setups, and impossible when you are pumping into a pressure tank for drinking water. The back pressure from the tank changes the operational characteristics as the pressure increases or if you have a permeate pump.

After a bit of thought, I realized that by measuring the TDS at three places you can compute the reject ratio quite accurately.
  1. TDS of input
  2. TDS of permeate
  3. TDS of brine

Reject ratio x = (TDS_in - TDS_permeate) / (TDS_brine - TDS_in)

i.e x:1 --- For every (x+1) input water volume, you will get (x) brine and (1) permeate output.

If you have a triple probe TDS meter, you can obtain the reject ratio without any re-plumbing and using measuring jugs.


km9830 is offline   Reply With Quote
Old 02/12/2018, 01:26 PM   #2
mcgyvr
Registered Member
 
mcgyvr's Avatar
 
Join Date: Sep 2003
Location: North Carolina
Posts: 15,603
Most systems are set from the manufacturer for a 4:1.. But yes if you plan to change restrictors/add dual membranes, etc.. then have at it...


__________________
Being blunt and having fun
mcgyvr is offline   Reply With Quote
Reply

Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On

Forum Jump


All times are GMT -6. The time now is 02:41 PM.


TapaTalk Enabled

Powered by vBulletin® Version 3.8.4
Copyright ©2000 - 2018, Jelsoft Enterprises Ltd.
Powered by Searchlight © 2018 Axivo Inc.
Use of this web site is subject to the terms and conditions described in the user agreement.
Reef CentralTM Reef Central, LLC. Copyright 1999-2014
User Alert System provided by Advanced User Tagging v3.3.0 (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.