Running dual RO membranes issue

[bcavalli]

I have been running dual membranes in my RO/DI for over a year now. I just came across an issue that I thought some of you may want to keep an eye on. Last week I noticed my pressure decreasing with the booster pump and replaced all filters except my membranes. I also noticed an increase in my TDS (25) going into my Dual DI canisters and 0 going out. I also started burning through my DI. After replacing all filters it didn't drop the TDS or increase the pressure. So I replaced my second membrane and that did the trick. The incoming TDS to my DI canisters are back down to 3 TDS and 0 out. I just thought those of you that are running dual membranes may want to keep an eye on your second one. Even if I have to replace a $30 membrane every year, it's well worth the dramatic increase in output.

 

[hnguyen]

$30 a year on membranes isn't bad at all. My 2 membranes cost me a total of $200 to replace and it hurts when I have to.

 

[bcavalli]

Hnguyen;1046666 wrote: $30 a year on membranes isn't bad at all. My 2 membranes cost me a total of $200 to replace and it hurts when I have to.

Wow what membranes are that expensive? Amazon has the exact same Filmtech membranes that BRS sells.

 

[hnguyen]

https://www.freshwatersystems.com/p-1440-merlin-ro-membrane-replacement-tlc-350.aspx">https://www.freshwatersystems.com/p-1440-merlin-ro-membrane-replacement-tlc-350.aspx</a>

My RO unit puts out nearly 800 gpd on a good day. Everything for is is more expensive then your normal RO unit.

 

[bcavalli]

Hnguyen;1046672 wrote: https://www.freshwatersystems.com/p-1440-merlin-ro-membrane-replacement-tlc-350.aspx">https://www.freshwatersystems.com/p-1440-merlin-ro-membrane-replacement-tlc-350.aspx</a>

My RO unit puts out nearly 800 gpd on a good day. Everything for is is more expensive then your normal RO unit.[/QUOTE]

Got it. Wow that's crazy. I'm only getting about 240 Gpd.

 

[reefkeeper]

I have a dual Membrane RO and I experienced the same type issue. I replaced both of mime and they and it resolved my issue. The membranes weren't cheap.

 

[hiimsean]

My production and pressure has been dropping too. Guess it's time for a new membrane.

 

[myreefclub0070]

HiImSean;1046713 wrote: My production and pressure has been dropping too. Guess it's time for a new membrane.

Sean, you should only be checking the pressure going into the membrane so if your having prussure issues that may cause your membrane to not work right.
Fix the pressure issue first and then check the out put tds of the membrane, also check you auto shut off valve.

 

[myreefclub0070]

Brett, I think it would only be right that the second membrane needs to be changed more often than the first cause it's taking in twice as much pollutants as the first.

 

[hiimsean]

I've got dual membranes and a booster. It's been a minute since I've changed the membranes.

 

[bcavalli]

MYREEFCLUB0070;1046735 wrote: Brett, I think it would only be right that the second membrane needs to be changed more often than the first cause it's taking in twice as much pollutants as the first.

That was my conclusion as well. But, I'll definitely take the trade off.