Replacing RO membrane
 

I've got a 75 gallon per day BRS RODI system. I've added a Aquatec booster pump to it so I've got a good PSI going. It's time to change the membrane. Can/should I upgrade to the 100 gallon per day membrane? Or should I stick with the 75 gallon per day membrane? I guess I don't really need a ton of water but will one be more efficient than the other?

No need to upgrade, then you would also have to change your flow restrictor.
Why bother? You can get a 99% rejection membrane from Spectrapure if you want an improvement.

Thanks Vinny

What is the difference between the 99 rejection rate and the quality filmtec membranes?

I have a 98% rejection using filmtec membranes with the appropriate flow restrictor(from Amazon for like 5 bucks) and some eBay sed and carbon 0.5 micron filters. 20 bucks for a set of 5-10 I forget. I bought a set of each and I go through it in 2 years.

Im sitting at around 100-105 psi. I got my RO system from Craiglist for 10 dollars.

Been doing it this way for a long time.

Your RO housing will fit a 25gpd to 150 gpd membrane.

Efficiency depends on pressure, temp, flow restrictor, flushing, appropriate membranes. I don't see why I would need a spectra pure membrane if I get the same results with filmtec.

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Spectapure is using Filmtec! Back in the day, I believe spectrapure. Did test the membranes first. I have a hard time believing that they still do. Filmtec membranes are shipped dry. Is spectapure still shipping wet membranes? And if they are shipping wet membranes they would need an expiration date because there could be bacterial growth on the membrane as they would have also washed off the preservative during the testing process!

The Filmtec in my Icecap RODI is rejecting 99.5+.https://uploads.tapatalk-cdn.com/202...699f09b5f7.jpg

Filmtec FTW!

I feel like many of us over-complicate the whole RODI situation.

We just need to call the city water department and ask for a breakdown of what they do to their water.

Then buy the appropriate filters/membranes for each scenario.

I've just advised a friend who was about to buy a whole new Spectrapure RODI system purely because he was getting 80 TDS post RO and burning through his DI in 2-3 weeks.

We found out that his PSI was like 30 and he didn't have a flow restrictor.

Saved him like 300-400 bucks.

Gotta keep it simple..silly!

As far as wet membranes go, I didn't realize that was a thing!

My filmtecs always come dry. I wonder why they would do that?

My membranes always come dry. One thing I learned the hard way is soaking the membrane for 24 hours before using it. I have not really read anything that states that the newer membranes need to be soaked but I put in a 100 GPD membrane that was dry and my TDS shot up from like 10 with the old one to about 80 with the new one. I tried everything including changing the housing and nothing fixed the problem. I popped back in the old one and it was back down at 10. My guess was that when 90 PSI hit the dry layers of the membrane it cracked some of them. I bought a new membrane and when I soaked that one and installed it the TDS was at around 8.
Now I just pre soak them for 24 hours and don't take any chances. Gon through about six membranes since then and all have been fine.

What I was trying to point out that if the spectrapure membrane is dry, they never tested it like they did back in the old days. Since the 75gpd membrane is supposed to 99% rejection rate, my guess is that they no longer pre-test them like they did when Filmtec were touting rejection rates of 96-98%

I’ve got the Icecap. Going on 6 months 150g tank with a few water changes and top off. Still haven’t broken thro my initial DI cartridge. Was worth the extra cash.


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For sure! I wish more people knew about it!

Sprectrapure no longer guarantees the 99% rejection rate, only 98%. They also rate the filter at 90gpd and not 75gpd. They do still state they hand test them on their site, not sure if that is still true. Mine is I believe around 2 years old and it did come wet. Seems like it also had an expiration date on it but I could be wrong about that. It brings my 450tds water down to 3 so I'm happy.

I was thinking my housing came with less than 25gpd membrane. Could be wrong about that, it is 25 years old.