Going the DI only route!

Discussion in 'DIY' started by sfsuphysics, Mar 13, 2006.

  1. sfsuphysics

    sfsuphysics Supporting Member

    Ok after much thought and deliberation I decided to do DI only, and hopefully within the next week or so I'll have my unit set up in the basement (where those who saw my tank on the tank tour).

    I'll be getting the resin from
    http://www.spectrapure.com/St_replac_p5.htm <-- for the bulk resin

    I have 3 resin containers, but will get a 4th (with resin already in it probably). The idea will be to use my existing RO unit's sediment & carbon filters without the RO membrane, then do 2 cation filters then 2 anion membranes, the resin is color changing so the idea is as one resin goes POOF I have the backup resin which should be nearly perfect (of course it'll be a little bit used, but that'll be one extra layer of cleanliness), then I can recharge one resin while the system is still "working" not to mention I can make sure one resin is completely exhausted before recharging.

    Thought about being a group buy on this, but to be perfectly honest the cost between buying a gallon of the stuff and a quart is really not that much savings, and the shipping isn't terribly much to start with (8 pounds cost about $13) that it really doesn't make much sense at this point, not to mention I dont want to deal with the hassle of people from all over the bay, a few select people I wouldn't mind, but the rest of you guys? Pfffbt ;)

    I plan on ordering the stuff on Tuesday just to make sure it doesn't arrive on the one of the two days during the week that I'm gone all day, but we'll see how it works out and I'll keep people up-to-date on this.

    I know Norman has done this, but he individually separated a mixed bed resin I think, and I don't have that patience :)
  2. Mr. Ugly

    Mr. Ugly Past President

    Spectrapure - good enough for the lab, good enough for your reef :)

    I would have went that way instead of the TWP route if I didn't already have the gift card codes for whatever web site it was that I bought the stuff from.

    Mike, you can still borrow my resin separating tweezers if you want :)

    Do some pics and a how-to for your DI project. It'll be cool.

    DIYDI :)
  3. Elite

    Elite Guest

    yeah pics... It's time for me to replace filter for my RO/DI unit. I got 2 bags of DI resin. If I don't have to buy the replacement filter for the RO then that would be so cool :D ...
  4. Raddogz

    Raddogz Guest

    So what is the TDS after running it through DI only?
  5. sfsuphysics

    sfsuphysics Supporting Member

    I haven't actually hooked it up yet, been way too busy/lazy, but assuming there's time this weekend I should be doing that then, or if not then spring break is next week and that means I get the week to do all fish related stuff (like finding a diamond tipped dremel bit to cut some glass!)
  6. sfsuphysics

    sfsuphysics Supporting Member

    Ok Eileen I think a water change is in the works (been a tad lazy!) so I set up the unit. Before I moved it, 1 sediment, 2 carbon, 75gpd RO, mixed DI resin I got 195 TDS from the faucet, 28 from the RO only, and 2 from the RO/DI now I'm sure the calibration on my TDS meter is off but it lays a good baseline.

    I hooked up the dual cartridges (which basically are those small DI resin ones that snap onto the RO unit) and I got 15, I put another DI unit after that and it got down to 2 again, so it seems to be yanking everything out this way as well. My guess is there's a limiting factor on contact time, where as before the 75gpd membrane insured longer contact time with the resin, without it though water squirts through quite quickly so may not be doing all it can. So you can put a flow restrictor if you want, or do what i did and just make a longer resin pathway (ie more chambers or a longer holder), I barely dented the 1qt of Cation & 1qt Anion I got so it's not a matter of not having enough. Another thing is it may just have been the initial squirt through I neglected to test it with just 2 chambers today.

    Over all I'm quite happy. I think if you have a RO/DI unit what you could do is get creative and Tee off a bipass to the RO membrane if you're that picky about water quality, and use that for the planned fill ups, and use the DI only for emergency "I need water NOW" situations, although from the TDS readings it seems the DI only is just as good as the RO/DI together.
  7. Elite

    Elite Guest

    If you slow down the input, will that work??
    Want post some pic of your DI unit?? :p
  8. sfsuphysics

    sfsuphysics Supporting Member

    imagine a regular RO/DI unit, except without the RO part, and 3 DI canisters, and tada :)
  9. Mr. Ugly

    Mr. Ugly Past President

    DI without RO works great. You get faster rate of production without wasting water. THe RO part of the process is slow. My DI only setup does 7.5 gallons per hour.

    The benefit of RO is that you don't have to replace or recharge resin as often. Not having to buy resin or handle "nasty chemicals" has been cited as one of the benefits.

    If you don't have a problem with doing the recharging process, DI is great. Our entire lab buildings complex used to have a DI only setup on the roof. We switched that out to a distillation unit, but it's had so many problems over the years, that we're going back to DI.
  10. Raddogz

    Raddogz Guest

    Wow, that's not bad at all. It certainly is something to think about. I am not looking forwards of filling up 100-120g of water for the new tank and I don't want to use tap water either.
  11. sfsuphysics

    sfsuphysics Supporting Member

    Hey Norman, where the heck can you get the lye & acid? Home Depots/Lowes around here don't have the muraitic acid (no pools), and the closest thing to red devil is a liquid generic "industrial" strength drain cleaner, it says it has Sodium Hydroxide, but also says potasium hydroxide in it.
  12. Raddogz

    Raddogz Guest

    muriatic acid is at OSH in so. sf.

    HD at least said they stopped selling it a couple of years ago - I asked one of the HD in Colma two years ago and they said they stopped selling it.

    Target in Colma may have it too.
  13. Mr. Ugly

    Mr. Ugly Past President

    Got my HCl at the HD off the High St. exit in Alameda/Oakland.

    I got the Red Devil NaOH either there or at an Ace Hardware... don't remember which.
  14. Vincerama2

    Vincerama2 Evil Overlord

    I've actually seen Muriatic acid at a HD not too long ago, the one in Foster City, FYI.
    I've seen it at OSH as well. It's Hydrochloric acid, right?

    Can you DI guys go over what you need to do to recharge the resins? And what kind of container are you using for the DI cartridged? Are you just using water filter holders?

    I think my RO membrane has stopped working, or has been punctured or something, so I'd be quite interested. Also, got pics?

  15. sfsuphysics

    sfsuphysics Supporting Member

    Well I've changed my mind on the DI only route after I went through resin so f'ing fast it was unbelievable I decided the membrane is fine enough then I hooked up a triple DI resin system to just make sure I nab everything :)

    Its really one of those things where cutting corners to save a buck is worth more effort than I get.
  16. Raddogz

    Raddogz Guest

    How many gallons do you think you made before the media was exhausted?
  17. sfsuphysics

    sfsuphysics Supporting Member

    Well I had a 3 line system, first two were the separate resins, the 3rd one was a left over mixed bed replacement and I probably got 40-50gallons before that 3rd one was completely brown (which makes me wonder if the first two actually took anything out). After that I noticed the separate beds started changing color so at that point I simply put the RO membrane back into line.

    Now it could have been some residual crap in the lines since it was in some old galvanized piping that I haven't used in years, although I did try to flush out the pipe as much as I could, but who knows.
  18. Mr. Ugly

    Mr. Ugly Past President

    Residual junk in the lines could do it.

    Also, with my mixed bed resins, the first use doesn't seem to produce much water before exhausting the resin. After recharging, they last way longer. I haven't quantified because I haven't standardized on my setup yet, but I've made up quite a few Brute container loads of DI on the current recharge.

    I'd been running 2 separated beds to partial exhaustion, but lately I collected more components so I could run a 3rd mixed resin cartridge. I'll probably head toward running 2 columns of each resin after using up my remaining mixed bed cartridges.

    How about doing a recharge on your resins and seeing how much DI you can get from a fresh charge?
  19. Mr. Ugly

    Mr. Ugly Past President

    What volume of resin do you have in your cartridges? On an RODI system, the resin is only for final polishing. On a DI only, you need a lot more resin.

    Right now, I'm running cation, anion, and mixed columns. Each column is ~12"H x 2.5"D.

    So that works out to approximately half quart of each type resin in the system.
  20. sfsuphysics

    sfsuphysics Supporting Member

    yeah I have those small 10 inch "polishing" containers for the resin, not the larger ones the size of the carbon housing.

    But yeah I've heard the first run might not be up to snuff because many places just sell used stuff or it might not be up to industry standards as far as how good it is. Still seems like a lot of work, more so considering I couldn't find any of the components, Red Devil Lye isn't made any more, I found some other drain cleaner that has some similar components but then it had some other stuff in there which I didn't know if it'd be good or bad, and hey I'm not going to risk my tank on something to save $20 every few months.

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