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How To Test Your Ro Rejection Rate

David Taylor

Active member
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603
(tap tds - RO tds) divided by tap tds x 100

90 1 = 89 90 = 0.98 98.89%

If your RO falls below 80% it time for a new one

DO not have your DI in line.

Edited for spruce who likes to be exact so i added the 0.89%

 
Your efficiency is closer to 99%.

Personally I replaced my membranes before that. As they become more inefficient with age, your resin costs will increase.

We have the di vessel after the membranes and then process pure into the IBC tank. The reason why we do this is because 3 of us use the water = 1 di vessel not 3.

At the moment there is no need for you to connect the di vessel up as cleaning with a tds of 1 will be fine. I would only start to add a di vessel when the water purity gets to 4. But then that's me and it's up to you and how you feel.

 
Well they say change at 90% but 80% is a must, after this your wasting your time.

It was just so people could check how their RO was performing.

I have a small 10 inch DI vessel after 2 x 40 inch, but like you i don`t need to use it really.

Static RO system connected to van at night so pure str8 into 900lt van tank

 
Your efficiency is closer to 99%.
Personally I replaced my membranes before that. As they become more inefficient with age, your resin costs will increase.

We have the di vessel after the membranes and then process pure into the IBC tank. The reason why we do this is because 3 of us use the water = 1 di vessel not 3.

At the moment there is no need for you to connect the di vessel up as cleaning with a tds of 1 will be fine. I would only start to add a di vessel when the water purity gets to 4. But then that's me and it's up to you and how you feel.
So would I personally....
 
If I used that method (if I had a 900 ltr van tank) my van would be sat on the driveway (if I had a driveway) for approx 48 hours waiting for it to be full using my 300 gpd ro /emoticons/biggrin.png

Unless you use a lot of water each day (800-900 ltrs) why do you have such a big tank?

Static RO system connected to van at night so pure str8 into 900lt van tank
 
If I used that method (if I had a 900 ltr van tank) my van would be sat on the driveway (if I had a driveway) for approx 48 hours waiting for it to be full using my 300 gpd ro /emoticons/biggrin.png
Unless you use a lot of water each day (800-900 ltrs) why do you have such a big tank?
2 ppl can easily use 400 litres each per day, I like quite high flow rates.
my twin 40 makes it like i`m filling it from the tap.

 
/emoticons/biggrin.png

89 divided by 90 x 100 = 98.88889% efficient

To check. 100 tds in - 98 out is 98% efficient - easy to work out in your head. On a calculator 98 divide by 100 x 100 = 98%.

Apply the same 'formula.'

 

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