View Full Version : RO Flow Restrictor

04/15/2009, 05:54 PM
I have a RO unit and I recently purchased a new membrane for it. It came with a flow restrictor, which I was instructed to place in the waste water outlet. The Unit produces waste and clean water with and without the flow restrictor, but with the flow restrictor the rate of waste water is lower than without - which I would expect.

Now my question, does using the flow restrictor shorten the life of the membrane or worsen the quality of the clean water, or does it just reduce the quantity of waste water produced for a given level of clean water?

Thanks in advance!


04/16/2009, 10:34 PM
Membranes are designed to produce at a ratio of four gallons of waste for every gallon of pure water produced. Without the restrictor you are wasting huge amounts of water and producing very little. Membranes generally last two to three years and the restrictor is needed so keep it on.

Wow Will 2 posts in 2 1/2 years you are really are in the backgound but I feel like I'm in good company with Steve.

This must be my week to meet Brazilians. A young lady landscaper from Brazil came to my house yesterday to help me with my yard design project.

Hope I answered your question

04/19/2009, 03:06 PM
Thanks for the reply. This will make it 3 posts in 2 1/2 years! I have the restrictor on and the clean water flow seems about right. I hope now the new membrane helps with the red cyano algae problem that has been steadily increasing in the aquarium.

Brazilians do pop up everywhere -- but actually I am English!


04/19/2009, 06:59 PM
Cyano is more of a problem caused by overfeeding then anything. A lot of hobbyists would like to think it is their filtered water that is the issue, But in most cases if they have a properly working RO/DI their water is the purest thing they are putting into the aquarium. Take a look at this link it might give you a little insight into Cyano.

I have a habit of either bringing out the best in people in posting on threads or end all posting and kill the thread.



04/26/2009, 03:36 PM
Hi! Am Hijacking this post - sorry. I'm not really understanding the restrictor thing, but why is there so much waste water! I hate that about my R/0 and understand it is the nature of the beast. I do not have a reef tank, but I do live in L.A. and have sharks so I hear yes I should use r/o only - water sucks - or no problems with regular water if no reef. What is your absolute total opinion on the above, thanks for your time.:rollface:

04/26/2009, 03:52 PM
Yes you need the filtration the RO provides to bring the tap water nutrient level down and remove the disinfectant.

Four to one Membrane waste is the nature of the beast and we have found one way around it. Dual membrane systems waste far less water if you have proper pressure at 65 psi or higher. The waste ratio is under 2 to 1 and what you are doing is making a 20" membrane and utilizing more of the water. It would be considered very green and something we should all be looking at for water conservation.