RO/DI Membrane help

Manose · Apr 7, 2023

This is my unit bought in 2018 so it's time for a new membrane. I would like to get some expert opinions on switching to a different membrane such as a DoW that has higher rejection rate. (please read below)

This is my unit

My water pressure is not good so I have a boosterpump and it runs at 90psi.
Here is membrane I have now but I want to switch to one that has a higher rejection

150gpd Membrane | Melev's Reef

melevsreef.com

This is a low pressure membrane so will that make a difference?
What changes will I need to make if I go with a different membrane?
Here are pics of how the booster is attached

Its not about the money its about the quality of membrane as I don't want to skimp on that even if its a lower gpd.

Manose · Apr 8, 2023

I will just get the 93% rejection membrane

Opus · Apr 8, 2023

You would need a different flow restrictor if you go with a different gpd membrane.

Manose · Apr 8, 2023

Opus said:
You would need a different flow restrictor if you go with a different gpd membrane.

Yeah that’s correct and brs has a good selection but I need to find out where my flow restrictor is located.

Manose · Apr 8, 2023

I think going to duel 75gal ro membranes is my best bet by changing my current membrane to a 75 and add a 75 in series with the brs upgrade kit. Would I put a flow restrictor for 75 gal unit or 150?
I see that I need to put the restrictor on the second membrane on the drain line

Manose · Apr 8, 2023

I just don't trust this membrane as it is a company I have never heard of. Does anyone know about this CSM membrane?

150gpd Membrane | Melev's Reef

melevsreef.com

Opus · Apr 9, 2023

Manose said:
I think going to duel 75gal ro membranes is my best bet by changing my current membrane to a 75 and add a 75 in series with the brs upgrade kit. Would I put a flow restrictor for 75 gal unit or 150?
I see that I need to put the restrictor on the second membrane on the drain line

You still will have a lower % rejection rate because you are sending all the waste water from the first membrane to the second membrane. I don't know the combined rejection rate for the 2 membranes so I don't know if it is better or worse than the 150gpd. I don't think BRS does a test for it in their video but they might.

Personally, I would trust what Melev has on his site for RO. He has been doing RO for many many years.

Manose · Apr 9, 2023

Opus said:
You still will have a lower % rejection rate because you are sending all the waste water from the first membrane to the second membrane. I don't know the combined rejection rate for the 2 membranes so I don't know if it is better or worse than the 150gpd. I don't think BRS does a test for it in their video but they might.

Personally, I would trust what Melev has on his site for RO. He has been doing RO for many many years.

Yeah I like the guy a lot and would be best to stick with what's working

Opus · Apr 9, 2023

Manose said:
Yeah I like the guy a lot and would be best to stick with what's working

I just looked, and BRS has a 150gpd membrane that has a 98% rejection rate.

Manose · Apr 9, 2023

Opus said:
I just looked, and BRS has a 150gpd membrane that has a 98% rejection rate.

Wonder of it is a DoW membrane.

Opus · Apr 10, 2023

Manose said:
Wonder of it is a DoW membrane.

The question was asked on their website and this was the reply:

'While most membranes are produced in one of only a few manufacturing plants, the 150gpd membranes we carry are sourced from the same supplier but are not Dow-branded."

Manose · Apr 10, 2023

Opus said:
The question was asked on their website and this was the reply:

'While most membranes are produced in one of only a few manufacturing plants, the 150gpd membranes we carry are sourced from the same supplier but are not Dow-branded."

Yeah probably a good membrane but I will stick to this one from Melev’s. My water is good as its normally never above 5 tds when entering the di cartridge. So I will just use 1 micron sediment,carbon blocks and go with a good di from spectrapure.

Opus · Apr 10, 2023

Manose said:
Yeah probably a good membrane but I will stick to this one from Melev’s. My water is good as its normally never above 5 tds when entering the di cartridge. So I will just use 1 micron sediment,carbon blocks and go with a good di from spectrapure.

Spectrapure also has a 150gpd membrane. I'm a Spectrapure fanboy so I would go with them if it was me.

You must have fairly good water from a tds standpoint. Mine is 400 to 450 out of the tap so I use the Spectrapure select plus membrane and get 99% rejection rate, even after 3 years of use. I also use their .2 micron sediment filter.

Buckeye Hydro · Jul 11, 2023

Opus said:
The question was asked on their website and this was the reply:

'While most membranes are produced in one of only a few manufacturing plants, the 150gpd membranes we carry are sourced from the same supplier but are not Dow-branded."

No, they are not a Filmtec product.