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The Watcher
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2,046 Posts
Discussion Starter · #1 ·
I have a Deluxe Kent 35 gpd Hi-S R/o di unit. http://www.drsfostersmith.com/product/prod_display.cfm?c=3578+4395+4453&pcatid=4453Since I received the system I have been unable to get more than 5 gallons a day out of it. I just purchased a TDS meter and saw that my TDS prefiltration is around 430, post filtration it is at 130. Last November the TDS was at 3. The DI canister is used up so I know I need to replace that. I already replaced the carbon block and sediment prefilters.

Any clue on the cause of the slow filtration? The water pressure is at 70 psi. I got the unit used, it had been used once so I thought perhaps the membrane had been allowed to dry out.

Is there a place I can get a replacement 35gpd HI-S membrane for a better price then the $100+ ? How about DI filters?

Thanks for the help!
 

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Just send me a PM ;)
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16,796 Posts
I would contact airwaterice.com and get a new membrane. a 75 gpd will probably work in the membrane housing you have. but you will also have to have a new waste water restrictor as well. but to answer your question, yes, i think your membrane is toast.
 

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spaceman spiff
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11,769 Posts
It does sound like the membrane has had better days. As tony points out, make sure you get the right hardware if you upgrade the membrane, it's not as easy as just swapping them out (unless you get the same gpd unit).
 

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Premium Member
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5,051 Posts
Agreed, membrane is a goner. I had the same unit too and upgraded to a higher capacity membrane too, best thing I ever did! You won't regret it. Main thing I had to do was to buy a new flow restrictor and membrane, it was relatively easy to install.
 

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The Watcher
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Discussion Starter · #6 ·
Thanks for the input everyone! I ordered a new 75 membrane and a 75gpd restrictor. No more waiting days to make water hopefully :)
 

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The Watcher
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Discussion Starter · #7 ·
I received a new 75gpd membrane today from h2o-science, a seller on ebay. I also got a new di canister which is refillable. Plus a new 1 micron sediment filter and a 1 micron carbon block for $68.00 shipped. I just ran 10 gallons through in a couple of hours and tested the TDS. Results were at 0! w00t!!
 

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I just love happy endings :D
 

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Perfeshunal Hikk
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Glad you got it straightened out Tard. I have to try to find membranes for a 25gpd unit I have. Think I am going to remove the DI and use it for drinking water though.
 

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Premium Member
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17,355 Posts
Just a small addendum to this post, as I think the issue was the membrane all along as well, but some my see their rate of filtrate production drop suddenly within the last several months by as much as 50% for other potential reasons. This may have been due to a change in several areas due to your local water company dropping the mains presure to conserve water (and reduce losses due to leaks in the system). Measure you mains water pressure, if it is below 50 or especially if it is as low as 40 psig, then consider geting a booster pump for the pressure to bring your input pressure back up to 60 psig + to improve the rate of filtrate production. Spectrapure is now making a unit with a booster pump and regulator (and special restrictor) that only wastes 2 gal of water (some report 1:1) for each gal of filtrate, something to think about...
 

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The Watcher
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Discussion Starter · #11 ·
That makes sense. I live in La Crosse WI and as of yet we have not had a sever drought. One of the reasons I love living here, it is always very green. The pressure on my unit is always around 75-80 psi. But in other areas, out West and the South it makes a lot of sense.
 
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