Deionizer only instead of a RO/DI unit?

[Murftoo]

I've gotten frustrated with the amount of waste my RO/DI unit produces and how long it takes (I have low water pressure), so I was looking into alternatives...

My LF showed me their setup which was a commercial dual bed deionizer that produced no waste at all. I realize the DI resins would need to be replaced much quicker since they aren't going through an RO unit first, but faster water production and lack of waste would be worth it for me.

Is there any other reason why I shouldn't use one of these over a traditional RO/DI unit for reef water? Portable Dual Bed Deionizer or 3-stage Deionizer.

 

[Cory]

I dont think thats a good long term solution. Id buy a booster pump. Also if you have well water or high co2 water it eats up deion resin very very fast. Need a degasser for that.

 

[Potatohead]

A good booster pump is about $80. You will pay for way more in DI resin than you would just buying a booster pump. You can get a dual membrane, a booster pump and run it at about 90 psi and you will have about 2:1 waste ratio instead of your current probably 5:1 if your pressure is low. Plus the membranes will remove more TDS so your DI will last longer too.

 

[saltyfilmfolks]

No it works better.

I’d look a the Randy Farley article on it.
I was just looking at these for a FB group.
One of my lfs uses a smaller version after thier rodi couldn’t keep up.

Speed of exhaustion will be relative to use. Just like a standard rodi.
How bad is the water and how much are you making.

 

[JoshH]

How much TDS do you have from your tap water??

 

[Murftoo]

I will look for the Farley article, thanks!

TDS out of my tap is not bad... at 145 right now (and has no chloramines and is not particularly hard). I've seen it spike up to 300 here and there, but it's usually between 140 and 180.

 

[Cory]

Thats pretty good tds. On my city well water i have 500-900 tds. My ro brings it down to like 7-16ppm. But co2 eats up thr deion.

 

[TheEngineer]

The capacity of a standard DI cartridge is around 8000 ppm of TDS. That ignores CO2 though. If you are putting in 140 ppm water you’d be able to run something like 60 liters of water before exhausting the resin.

I think that math is right.

 

[AquaFX-PB]

So @ 5ppm with no Chloramine/no Gasses or other gremlins, a mixed bed DI (10 x 2.5") - will last approx 1000 Gallons.

Youre at 29 times that amount - so we can pretty safely say that the same amount of DI resin would last approx ~ 35 Gallons.

Now you can quickly see the benefit of running RO before the DI.
Hard to beat the rate of production with a straight pass thru, but be careful because even DI resin has some amount of a "coefficient of contact time". So if the water passes thru too fast, you could have TDS break-thru. But the large resin bed (the tanks you showed) will help to allow for more contact time vs a 10x2.5" clear canister full of DI!

just more costly per gallon of water.