Will RODI GPH decrease with long output line?

Clownfish2 · Apr 25, 2020

Will RODI GPH decrease with long output line?

I’m planning to install my BRS RODI 6 stage with booster pump in my garage. I need to run the output line either up the wall 4ft or down to floor and to the other side of garage about 20 feet where my mixing station is located. Will this long run decrease RODI output?

Currently, I’m getting 76-78 psi on booster and using an output line of about 4 feet.

Phillthy · Apr 25, 2020

It shouldn't effect the output.. Your just going to hold alot of water in the line so it might be slow to start but aslong as the pressure is good and no restriction on the input your good

NowGlazeIT · Apr 25, 2020

Yes it will slightly but you have a booster pump, should be fine. My 6 stage runs at 55psi and I’m happy with the filter longevity and water production.

malacoda · Apr 25, 2020

Just a heads up -- AFAIK, 76-78 is a bit too high for output pressure. It's my understanding that optimal is ~50 and anything more could wear out your membrane quicker. You may want to adjust the regulator on the booster ... or remove it altogether if you've got ~50 without it.

Double check with the RODI manual/manufacturer first though as I'm not 100% certain.

NowGlazeIT · Apr 25, 2020

malacoda said:
Just a heads up -- AFAIK, 76-78 is a bit too high for output pressure. It's my understanding that optimal is ~50 and anything more could wear out your membrane quicker. You may want to adjust the regulator on the booster ... or remove it altogether if you've got ~50 without it.

Double check with the RODI manual/manufacturer first though as I'm not 100% certain.

Cool I did not know this! Makes sense for my situation. my membrane is 3years old and my rejection rate is the same as the day I bought it. I also flush the membrane in the beginning, during use and at the very end each time.
60g cube with 15gal sump

(1st)Sediment (2nd) 5 micron carbon block (3rd)1 micron carbon block (4th) Dow membrane (5-6th) Mixed DI

Phillthy · Apr 25, 2020

Do some research. Ive read higher pressure is better going in. And will make units last longer. There is barley any pressure going out from the rodi... most is waste water. Having 70-80 psi on the input is best. And I dont think the length of the output line will affect anything other than travel time to your storage container.

Clownfish2 · Apr 25, 2020

Thanks for the help! Let the fish room begin!

ca1ore · Apr 26, 2020

I have a long output line on mine and it seems to make very little difference. I will say, however, that my booster pump did not like a long input line. Made all kinds of funky noises. So I moved the unit closer to the source tap and lengthened the output. Works fine that way.

Phillthy · Apr 26, 2020

ca1ore said:
I have a long output line on mine and it seems to make very little difference. I will say, however, that my booster pump did not like a long input line. Made all kinds of funky noises. So I moved the unit closer to the source tap and lengthened the output. Works fine that way.

Wich end of the long input line was your pump on? Next to rodi or next to water supply?

fishbulb · Apr 26, 2020

A longer output line will have more serial resistance, so yes, it will decrease output. There is a type of flow restrictor that is essentially a long tube that inserts into the waste line of your RO unit. You would trim this flow restrictor so that you get your 4:1 waste to pure ratio. You would trim this with your very long waste line attached. Essentially, you should be trimming your flow restrictor to account for your long waste line.

In practice, it likely won't matter too much. You could also increase the diameter of the waste line to decrease the axial resistance.

CHeers,
FB

ca1ore · Apr 26, 2020

Phillthy said:
Wich end of the long input line was your pump on? Next to rodi or next to water supply?

Not sure I really understand the question. If the booster was next to the supply then it wouldn’t have had a long input line. It did occur to me the just move the booster, but the lines that connected to the pressure shut off switch were too short so it was easier just to move the entire thing. Thought about re-sweating a closer supply stub ... but propane torch was empty LOL.

Phillthy · Apr 26, 2020

ca1ore said:
Not sure I really understand the question. If the booster was next to the supply then it wouldn’t have had a long input line. It did occur to me the just move the booster, but the lines that connected to the pressure shut off switch were too short so it was easier just to move the entire thing. Thought about re-sweating a closer supply stub ... but propane torch was empty LOL.

You stated your booster pump didnt like a long input line. Made noises. I was curious what end of the line your pump was on. Next to the source tap or next to your rodi before you moved it?

Phillthy · Apr 26, 2020

I have a long supply line from my laundry room. Roughly 50 ft. 1/4 in od rodi line. My rodi system is in my fish room. I need a booster pump but not sure what end is best to install it on.

ca1ore · Apr 26, 2020

Phillthy said:
You stated your booster pump didnt like a long input line. Made noises. I was curious what end of the line your pump was on. Next to the source tap or next to your rodi before you moved it?

My system is water source to particulate/carbon filters to booster pump to RO membrane. With a 20’ initial run of 1/4” tubing from source to first filter stage the booster pump was unhappy. Reduced it to 5’ .... much happier. Since the booster ideally is after the particulate filter stage, not sure how you’d install it remotely.