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RODI Membrane Questions

Discussion in 'General Discussion' started by phishcrazee, Feb 7, 2011.

  1. phishcrazee Experienced Reefkeeper

    Riverside
    Ratings:
    +0 / 0 / -0
    I think one of ours needs replacing, but seems like it wasn't that long ago we replaced it.  *Maybe* 2 years ago, but I don't think it was even quite that long ago........the last time we replaced it, the taste of the water was bad (we use it as drinking water as well as tank water), even after all the filters and resin were replaced.  So the water has been tasting funny again and so we replaced all the filters and resin and things were good for about a month, then the bad taste started coming back, so now I'm thinking its the membrane that needs to be replaced.  We have always used quality membranes and filters and replace the filters ~every 6 months or so, but have very hard well water (we do have a softener though).  How often are people changing the membranes out?
    Also, my husband seems to think we can just take the membrane out on this RODI unit, since we mainly use it for drinking water now and use the RODI unit downstairs for tank water.  He says the membrane is just for taking out the salts in the water and  that it doesn't really matter for drinking water.  He's also a little cheap /DesktopModules/ActiveForums/themes/_default/emoticons/rolleyes.gif I've tasted the water that has only gone through the filters though and I think it tastes funny.......can anyone tell me more about the function of the membrane?  I've looked at BRS and it seems like any RODI unit should have one, but then again, they are selling a product.......
     
  2. Guest

    Guest Guest

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    you can try back flushing the membrane as far as you getting salt in to the water the watersoftner will go in to back wash it will suck up 12 -14 pounds of saltwater out of your brinetank after it cleans the resin in side then tank it back flushes the saltwater and gunk down the drain then it fills its self back up with clean water and goes it to what is called the final rinse to make shure all the salt is out of the tank so thair that you dont get salt in to your drinking water you can get a permate pump that will help big big time on your membrane and water waste if you take out the membrane the unit is worthless a good membrane is only 30.00 with free ship if you use like the menard fillter them are cheap cheap and wont last you need a really good fillter look up pentex gac-10 is what i use for carbon and p5 for a prefillter and a tfm 100 membrane did you check your tds ?  you might just need to put new carbon fillter in thair good ones
     
  3. Bud Loves Bacon Website Team Board of Directors Leadership Team GIRS Member Vendor

    West Des Moines, IA
    Ratings:
    +1,821 / 14 / -0
    Just curious - what do you mean by this?
     
  4. jsprague

    jsprague

    184
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    +0 / 0 / -0
    If you remove the RO membrane it should be fine for drinking water.  Most of the units made for household use are just a sediment and a carbon filter.  That's how mine is.
     
  5. jsprague

    jsprague

    184
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    By the way, if the ro unit is plumbed to your refrigerator for ice/drinking water, the fridge may have its own filter that needs changed.
     
  6. vikubz Well-Known ReefKeeper

    734
    Cedar Falls
    Ratings:
    +8 / 0 / -0
    Do you have a tds meter to check the output from the ro stage?
     
  7. Bud Loves Bacon Website Team Board of Directors Leadership Team GIRS Member Vendor

    West Des Moines, IA
    Ratings:
    +1,821 / 14 / -0
    Sorry, I didn't read it close enough. Yeah if you remove the RO filter it's better than nothing, but if your water tastes funny after going through the pre-filter stages, then there something small enough that is getting through, or your activated carbon is used up.

    I know that when my carbon gets used up, the RO water gets a funny rubber-like smell. It's really quite odd and it took me a while to figure it out.
     
  8. AJ

    AJ Inactive User

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    From most of what I've read, a membrane will last a couple of years for most people. If you have really hard well water, I'm sure that it reduces the life span. Your sediment and carbon filters should probably be replaced at least every 6 months...maybe even quarterly for well water. If the taste/smell is bad, replace the carbon filters and see if that helps.

    Your membrane takes out more than just salts. It takes out other trace elements, bacteria, and other stuff that may be in the water as well. Living in Iowa, there's all sorts of great stuff that can be in the water from chemical run off and stuff. Here's a link to the CDC page about well water (http://www.cdc.gov/healthywater/drinking/private/wells/). There may be some helpful into in there. If I used a private well for drinking water, I *would not* remove the membrane as it's what does the majority of the filtering work.

    An RO membrane will reduce output when it gets old and toward the end of life. Also, you can look at the rejection rate. Measure water going into your RO unit, then directly after the membrane. If your membrane is rated for 97% rejection rate, then your output should be around 3% of what the water going into the RO unit is. As your membrane gets older, it will not reject as much and your TDS will creep up. Whatever your TDS is right after your membrane is what your DI resin will need to handle. The higher the TDS, the faster you'll burn thru the resin. I wouldn't use a membrane that had TDS output higher than 20 or so.

    If you need to borrow a TDS meter, let me know. I have one you can borrow.

    --AJ
     
  9. phishcrazee Experienced Reefkeeper

    Riverside
    Ratings:
    +0 / 0 / -0
    Thanks all, I think I'm going to go ahead and replace the membrane, as we just replaced all the filters about a month ago and now the issue is back. Can't afford to replace filters quite that frequently /DesktopModules/ActiveForums/themes/_default//emoticons/smile.gif We have an inline tds meter on the unit. Since hubby bipassed the membrane, I cannot tell what the after-water tds reading would be. Right now, it sits at 267 just with the filters :S
     
  10. AJ

    AJ Inactive User

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    After a new membrane is installed, your TDS should go down to 10 to 15. You ordering from AWI? If so, let me know and I'll split shipping with you as I need some new filters and DI.

    --AJ
     
  11. phishcrazee Experienced Reefkeeper

    Riverside
    Ratings:
    +0 / 0 / -0
    I usually get my RODI stuff from Bulk Reef Supply.......what's AWI?
     
  12. AJ

    AJ Inactive User

    Ratings:
    +0 / 0 / -0
    Air, Water, Ice. They're a club sponsor (as is BRS), but specializes in water filtration. Great prices and customers service...plus, members get 10% off. See Power Buys in member forum.

    --AJ
     

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