So what are people using for a RO/DI system?

Discussion in 'Equipment' started by sfsuphysics, Oct 21, 2017.

  1. xcaret

    xcaret Supporting Member

    Canisters are clear...
  2. sfsuphysics

    sfsuphysics Supporting Member

    That could be useful.
  3. Vincerama2

    Vincerama2 Evil Overlord

    Mine started life as an AquaSafe RO/DI unit, then over the years I've replaced a lot of part so that not even the original bracket is in use. So mine is just an RO/DI unit that gets parts replaced as needed. Not even really a "unit" anymore so much as a bunch of parts.
    ashburn2k likes this.
  4. sfsuphysics

    sfsuphysics Supporting Member

    Really need to use the TDS tester more often, about 80 coming out of the RO membrane which is a definite sign of membranes being toast (or a bad TDS meter :D). Explains why my DI resin went bad so quickly though. Oh well, new membranes on the way (amazon prime) and some parts from BRS to throw together a 3 stage DI resin area (Cation, Anion, Mixed Bed). Well see how well that works out. I was leaning toward 20" filters for the resin, but now I'm thinking that may be a bit overkill.
  5. rygh

    rygh Supporting Member

    I have a simple 4 canister + extra pre carbon filter. Color changing DI is refillable, saves money.
    Extra carbon for Chloramines, seems to increase life of DI resin.
    I really think people worry way too much about water quality in.
    You look at all the food you put in, and it WAY dwarfs and nitrates/phosphates from RODI.
    For me, I just want to make sure no copper or Chloramine gets in.
  6. sfsuphysics

    sfsuphysics Supporting Member

    That would be something interesting worth looking into the numbers. What's 2 teaspoons of food in 200 gallons of water translate to?
  7. RandyC

    RandyC Supporting Member

  8. sfsuphysics

    sfsuphysics Supporting Member

    Seems to be counter intuitive to what Mark is saying though, it says adding 1 reef prime cube is the equivalent of adding 0.022ppm of phosphate daily, so double that and we have 0.044ppm. If you had a TDS reading of 4.4 ppm that's 100 times more. Granted TDS is not simply phophate (if it is at all phosphate), but seems to be having dirty water actually adds a crap load (yes pun intended) of stuff to your aquarium above and beyond phosphate.

    Now that real question is what exactly are the dissolved solids that make up TDS.
  9. rygh

    rygh Supporting Member

    Don't bother with TDS for that. Just check phosphates with a test kit directly.

    But sorry, I did not mean to imply you should use tap water directly. That could introduce a lot of phosphates.
    After RODI it should be very low.
    But of course, if RODI is not working....

    My favorite article on phosphates

    And a key quote:
    "... if five grams of flake food is added to a 100-gallon aquarium, there is the potential for the inorganic orthophosphate level to be raised by 0.4 ppm in that SINGLE FEEDING!"
  10. sfsuphysics

    sfsuphysics Supporting Member

    Well yeah after RO/DI .. I'm going to assume it's working unless TDS says otherwise. I just want to set things up for ultimate "ease of use", whether that means maintenance on filters (hence the discussion of the 20" filters) or ease of packing resin into those little containers (which always seems to be a pain in the ass for me which is why 10" might be best even if I have to change it twice as often as a 20" cannister).

    5 grams of flake food is a lot though, 1/14th of those smaller Ocean Nutrition cans.
  11. xcaret

    xcaret Supporting Member

    Haven't forgotten about the clear canisters, just been busy a little more than usual. As a side thing, I picked pair of the long canisters on a bracket, they have carbon blocks but they are white.
  12. sfsuphysics

    sfsuphysics Supporting Member

    No worries Mario, the solid ones I have will do for now. I'm just thinking about the DI resin canisters. Unfortunately BRS is all out of the Anion resin, seems like a lot of other people are doing the separate bed method.
  13. L/B Block

    L/B Block Supporting Member

    At the end of the day, the tds in Oakland where I am is 30. As such, good or bad, I have a three stage with a sediment filter and two carbon blocks followed by a two stage DI. It eats up the DI media probably faster than expected to last but all seems ok with the system and no water waste from RO.

    Sent from my iPhone using Tapatalk
  14. Coral reefer

    Coral reefer President

    I still don't understand why you don't just use 2 membranes in series to minimize waste water, and then use the waste on your yard... if you're willing to use salt water in the yard certainly waste water from ro will be fine.
  15. L/B Block

    L/B Block Supporting Member

    Didn’t realize that was an option per se.
    The salt water has to be discarded and can’t be avoided though -we could potentially hose discarded RO water to the yard but if we can do away with any waste water upfront all the better with the current system!

    But my question is-if I am starting with 30 tds and ending at 0 with the DI where is the value add? What else is the RO doing that chloramine blocks and DI isn’t doing?

    As to the main elements -Alk, Ca, ammonia nitrates, phosphates are all fine (last I checked last week) and fish are happy. Most of the corals seem ok. Maybe something in not doing so is zinging the acros?

    Sent from my iPhone using Tapatalk
  16. sfsuphysics

    sfsuphysics Supporting Member

    There's no waste water from RO because you don't have RO :) You simply have a the equivalent of a Brita type of filter.

    Which having 30 TDS is great, and if not "wasting" water is important to you, then what you're doing is probably fine just costs you a bit more, RO membranes can knock the TDS down to 95-98% of what they were, so it really doesn't matter your TDS, you'll use resin 20-50x faster without a membrane than with. But if you don't make that much water then it probably isn't a huge cost to you.

    That said though I would worry doing resin only simply because water is going to be moving faster through the resin, leaving less contact time to remove stuff. A quick google shows you can easily get 1 GPM through 1/4" tubing with household pressure (probably a bit less after the filters, so lets say half that). at 0.5 GPM that means 720 gallons per day, which is about 10x faster than most single membranes so 1/10th the contact time with your resin.
    Coral reefer likes this.
  17. L/B Block

    L/B Block Supporting Member

    If I had a much bigger water demand per se, I would probably think more about it-or if the tds was at 200-400 as other BAR members have reported it would change my tune.

    Right now -incorporating the DOS to regulate the water changes, total water demand is prob close to 40 gallons with ATO total.

    Good to point out the contact time. The readout from the TDS line out is 0 so I assume it’s doing it job?
    I’ll look into membranes though and do the math.

    Sent from my iPhone using Tapatalk
  18. sfsuphysics

    sfsuphysics Supporting Member

    Well I always say is if you have something that is working (over a long period of time) even though it "shouldn't" then keep doing it! :D

    Having 0 TDS might be a bit of a false sense of security though, since TDS only measures the conductivity of the water due to dissolved ions. Things like sugars, organics (pesticides), and other things won't be detected at all. But again if what you have has been working (more than a month) then no sense in rocking the proverbial boat.

    p.s. I'm not super smart about water chemistry, I borrow all my information from people who are <-- article on TDS
    Coral reefer likes this.
  19. L/B Block

    L/B Block Supporting Member

    Thanks for the link. I will certainly read. It’s been a real education relearning water chemistry and still far from understanding it all.

    I rely on the tds metering for well-tds!
    As for more organic/bacterial issues-that’s what chloramine is for and from my understanding does a good job at removing those elements so less concerned about it in the tank-just need to get that back out prior to filtration.

    Sent from my iPhone using Tapatalk
  20. Coral reefer

    Coral reefer President

    Di resin isn't cheap and is hard to store once the package is open. You will use WAY less if you use the membranes which will last several years in your case and cost maybe $100 for 2 will the housings. That being said, you do need good water pressure to make it work, or another $100 for a booster pump. Not sure how's long your di resin lasts, and as for the contact time issue maybe 2 canisters of di in a row would help.

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