RO/DI price difference

[zman1]

Chip I agree with everything you have said here in this thread. There isn't any magic between one unit or the other. Filters that come with a unit regardless will need to be changed. I myself would pick the best price one. If folks haven't seen one or not seen a parts breakdown of these units, then they may believe one has magical powers over the other. They all use standard size filters for RO/DI, If you find one that doesn't, then I wouldn't buy that one.

 

[chipmaker]

It seems to be that the biggest gripe a lot of folks that spend a few hundred dollars for an rodi unit instead of buying one like a Water Genral have is that the GPD rate is supposedly too high and that you have to have 60 or less to be worthy of putting the water in a reef tank. 0 is still 0 TDS or 99% is 99% no matter if it comes form a 20 or a 100 gpd unit. If it makes a person feel better to have a lower gpd rating all it takes is a toll free phone call and ask for Oscar at water general and tell him y want a 45 or a 60 gpd membrane installed in place of that 100 gpd membrane. Of course he is going to laugh and ask why, and then explain that your hearing bogus info, but will still do as requested at no additional charge. Been usuing 100 gpd units for over 2 years without problems. I just do not see where waiting for water should take me a weekend and then some to fill up a 90- or 150 gal tank.
About the only area I see a difference among all the manufacturers is in the DI section. Some have sealed throwaway carts, others have rechargeanble single carts others have double refilable carts.......all of which are fine, but you will find refilable carts cheaper overall to maintain, and the di media is also able to be recharged and reused over if your into that sort of thing. A disposable cart is tossed, so why but a new housing with di resin every time. IMHO 2 smaller chambers with DI resin ( which equal the same capacity of the larger chamber) is better than 1 large chamber since it lessens the chances of channeling. It really does not make any difference if the DI media is vertical or horizontal.

 

[zman1]

Chip -"About the only area I see a difference among all the manufacturers is in the DI section. Some have sealed throwaway carts, others have rechargeanble single carts"
Those are consumable and you can buy one at anytime. One that I know, SpectraPure DI 10" cartridge are re-fillable. Get one and then buy Resin in bulk. I myself haven't yet to buy bulk resin but that is on my list of next time. I have a bunch of the SP re-fillable cartidges, was throwing them away before I noticed they unscrew on the bottom.

 

[chipmaker]

My DI resin chamabers are also refilable, Only way to go IMHO. I bought a big container of resin and basically got about 40% of it for free with the price I paid., I figured heck its not a one time deal and I intend to use the rodi units so its not like it will go to waste. I also have the junk neded to clean up and rejuvinatye the di resin but have not gottenaround to playing with that yet. My lfs here sells throwaway carts of di (about 12 ouonce capacity for a whopping $21 each. I have seen a bag of di resin which contained enough resin to recharge 4----16 ounce refillable carts for somehting like $15 or 18 bucks.....Not hard to figure there is not anything cheaper about a throwaway housing type cart. I also like to be able to see inside thre di carts sop I can keep an eye out for any channeling, wich is very common occurance with lots of di resin carts, be it throwaway 0r refillanbles

 

[zman1]

The attached picture is what I was referring to. I have seen the sealed in-line canisters for DI you are talking about...

 

[chipmaker]

I seen those type. They wold be good to add to a setup that has the throwaway carts on it. The tuype I have looks just like the larger housings do, and made the same way only smaller. Double O rings on cap portion, but they are fed from both ends unlike the main housings which are typically plumbed on one end only.

 

[f14peter]

Originally Posted by chipmaker
YOu just can not look at having rodi for making SW. Its used on an almost daily basis for top off water as well. Around these parts the lfs sells sw for 80 cents a gal, and rodi for 65 cents a gal. Gas here is better than $2.60 a gal and my trip to LFS or just town to but rodi at Wally World would involve a round trip of close to 60 miles @18 mpg plus wear and tear on a vehicle, and even though I may be retired, my time is worth something as well. I priced a 5 gal bucket of salt about 2 weeks ago of INstant Ocean. LFS here sells it for $39.00 a bucket....and it would make 160 gal at approx 1.023.
For water alone and no other incurred expenses:
160 gal of premade saltwater would cost $128.00
160 gal of store bought RODI would cost $104.00
My monthly water bill is only $22, and in most areas $100 bucks buys a lot more than one months average of water.
If I use 5 gal of top off water a week, and 5 gal of SW a month its easy to see with the math a RODI can be paid for in short order. MOst folks just do not figure in vehicle wear and tear or fuel and their time.....
I'm on flat-rate water too, and it just makes too much sense to go with your own unit. As I mentioned earlier, I've run over 250g through my unit (with many many more to go), so even at 50cents/gallon store-bought, I figure my units will have paid for itself in about 3 months.