RO Membrain question

A

Angela Short

New member
Will any RO membrane fit my housing? My GPD output is about 15 from 100 and I just changed everything but the membrane with no improvement. It is still giving a TDS of 20 from the RO but a 0 from the Double DI but I know its burning my DI up. I have never replaced it so can I just order any replacement or do I need to order from the original manufacturer? Should I get a lower GPD and it would last longer? Mine was a 120 GPD. Thanks!
 
The membrane should be a standard size. If it were me, I'd get a Dow Filmtec 75 gpd membrane. It has 98% rejection. I get 0-1 TDS after my RO on my system with that membrane, and after about 2500 gallons I'm still on my first DI.

You can get them here:
http://theh2oguru.zoovy.com/product/TW301812-75

or here:
http://www.purelyh2o.com/home.php?cat=261

Since your membrane wore out so quickly, I'd look at the type of pre-filters you have. You want to have them filter out as much particulate (non-dissolved) stuff as possible, as well as get all the chlorine. Particles can clog the membrane, and chlorine damages the membrane. I have a Typhoon I from air water ice that uses a 10 micron sediment filter followed by a 5 micron carbon block, followed by a 1 micron carbon block. This gets all the chlorine, and filters particles down to 1 micron. The graduated nature of the setup (10 micron -> 5 micron -> 1 micron) ensures larger particles don't clog up the carbons. If it started off smaller, then the filters could clog more quickly...

At any rate, you should be able to swap out your current membrane for a better one like the filmtec.

You could probably call either place and speak with someone who could tell you whether or not the membrane would fit properly in your system or not. You could also try emailing walter at air water ice. He is who I bought my stuff from. I think his email is on the website of the first link above.
 
Yea I guess my cheaper ebay unit is proving to be more costley in the end! The replacement guts cost almost as much as the unit and I have 2 white prefilters of the same size and a carbon filter so it don't sound near as good as the stepping down prefitlers you have. Probably why it has wore out so fast. I have ran massive amounts of water through my membrane and we use it as drinking water also but I would still think it would last longer than a year..... Live and learn is the motto in this hobby I guess! Thanks!
 
Ok, so my question is exactly how often should you change out the pre-filters? My RO membrane is still giving me 0-1 TDS water before DI, but my prefilters (particularly the largest micron filter... not sure what size) are noticably turning brown. On top of it making me not want to drink my water, I'm concerned that it may be putting extra load on the more expensive parts of the filter. I haven't checked the RO rejection rate lately, but should I expect the rejection rate to increase as the pre-filters get dirty? Is there a general rule of thumb on changing them?

I've only had the unit 3.5 months and have made around 500 gallons.
 
I have heard that the rule of thumb on changing out pre-filters is 6 months. They can last longer than that, but 6 months apparently keeps things like bacteria, etc, from building up. Air water ice (where I purchased my unit) recommends yearly. The truth is probably in between.
 
Here is a general rules that I use.

micron filter if it is brown change it. They are cheap so no big deal to replace. The big one is the carbon filter. depending on the type you have you may want to change it every 2000 - 5000 gallons or so. The reason is chlorine will destroy your membrane. That is one of the things the carbon filter removes. For the DI filter, if it is color changing then when it has all changed to the other color change it or if your TDS coming out of your DI is not 0. For your membrane it should last about 2 years.

Hope this helps
 
Angela,

Sorry I didn't read your thread which I should have since it is your post.

If you are only producing 15 GPD on an 100 GPD it could also be caused by low water pressure (most will work with at least 50 PSI) or if you have a flow restrictor or a restrictor value on the waste line. Generally you should produce either a 4 to 1 or 3 to 1 (3 or 4 gallons of waste to 1 gallon of product water) or a bad membrane. Check the others first before replacing the membrane.
 
I hijack regularly Brian :) Still on subject is a good thing!

Sir Knight, I was producing great, up to specs for months, and TONS of water, but when I filled the 270 for like 4 days straight is when it went suddenly bad. I don't know if having it run 24/7 for days on end did it by letting to much through my already old pre-filters or what. I was due to change them but figured I would fill the 270 first then change them. I have had it going since about 1 today and have about 3 gallons :( I went ahead and ordered a new membrane but now am kinda worried about the quality of prefilters I have....
Thanks again for the advise!
 
Angela,

I don't know what your filter configuration looks like. Mine has 3 pre filters (1 sediement, and 2 carbons). I get my replacements from air water ice. A 6-pack is like $39. If you have 2 pre-filters, they also sell a two-pack for like $12 or so.
 
It has the 3 pre-filters 2 the same white kind (?) and 1 carbon. But I remembered I ordered some DI also is why my prefilters were so much. Still I know they don't step down, 2 the same and 1 carbon. I will go with your kind next go. Thanks for the help! I ordered the 75 you posted yesterday so I should be good to go.
 
Angela,

If I were you, I'd swap out the second sediment for an additional carbon block. Just added insurance... You only replace one at a time because the first one in line takes the brunt of the abuse. Swap the second one with the first one and put a new one in the spot of the second one.
 
I got the new filmtec 75 GPD membrane in yesterday. I was surprised to see how much gunk had came through to the membrane compartment. It had some nasty looking black residue like it came from the carbon block. I guess the cheapo prefilters are not so cheap if I have to replace my membrane every year....

Am back up to making water super fast again. So fast I overflowed a 5 gallon water container right off :( At least 2 gallons sitting on the hardwood before I noticed. Did a huge water change today of 60 gallons thanks to my new found GPD going again!
Installed a 21 gallon rubbermaid tub under the tank tonight for my auto top off so everything is finally put together and under the tank. All I need is some fans for the canopy now to be 100% done. I wrapped the tub in that plummers hanging stuff and tied it with 18 gauge fence wire then taped it around so it doesn't slip. Its filled now and not bowwing bad at all.
000_1286.jpg
 
Angela,

I got a float valve from All Seasons (near green hills mall - http://www.allseasonsnashville.com/). It looks like this:

ffloat_val


If you drill a small hole in the top of your water bin, you can install the float valve and run the RO/DI tubing into that. When the bin fills, the float valve stops the flow. You also need to have an auto shutoff valve on your RO/DI for that to work. Many units come with those so maybe you already have that. I use float valves to ensure I don't make a mess ;)

ASO Valve:
asov_best.jpg


Here is how I plumb my water out of my RO/DI unit. The top represents my topoff reservoir. I turn the ball valve every 5 days or so to refill it (no buckets :)). The bottom represents my usual RO/DI storage tank for mix up water, etc. Float valves on both keep me from having spills.

2000434RODI.jpg
 
Something that you may consider is the quality of water coming in. You know those dirty contractors don't clean all the debris out of the lines. I know that your area down there is really developing so you may get longer use as the years go on. WE will get call backs after new neighbors are put on the services or a big one is any type of road work seems to always involve a water line

Rob
 
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