RO vs. RO/DI

[Nrapp33]

What are the main differences between RO and RO/DI? How much more does the latter do for overall quality?
Looking at some significant price differences.

Thanks

 

[Gti_Leo]

deionization it takes out the remaining particals that the RO may have missed

 

[Nrapp33]

I hear ya. I live in St. Louis City and am on the same water system as the Anhesuer-Busch Brewery which has historically been very good water.
Anyone familiar with better water qualities and just using a RO unit?

 

[Gti_Leo]

i'd atleast go with an RO unit, but it never hurts to have extra filtration.

5 Stage 100 GPD REEF AQUARIUM REVERSE OSMOSIS WATER SYSTEM RO DI

Aquarium RODI

this is where i bought my unit, i have a combo drinking and aquarium. the driunking water doesn't go through the DI section but the aquarium does and it was well priced

 

[kay-bee19]

RO should remove 98-99%+ of TDS from tap water, but will still contain residual TDS.

The DI stage will remove the remaining TDS (basically removing what the membrane could not), producing 0ppm RO/DI water.

As an example with a 98% rejection rate, the RO membrane should reduce 350ppm-TDS tap water to 7ppm RO water. DI resin will then reduce that 7ppm RO water to 0ppm RO/DI water.

One thing to consider, if your tap water is treated with chloramine (a chlorine+ammonia disinfecting compound): the carbon block or catalytic carbon block stage will unbond the ammonia from the chlorine and adsorb the chlorine. The carbon block and RO membrane cannot filter out the remaining ammonia, however the DI stage can.

 

[hackteck]

i have a RO unit and it filters down to 1ppm on my tds meter thats good enough for me

 

[Nrapp33]

Kay-Bee,
So how would I find out what additives are in the water.
And regarding the final product of straight RO, ammonia? Please expound on this!

 

[melosu58]

It does not make much difference if you have the best water in the country. The water municipality that I work for is supposed to be in the top three in the country. It`s what is used to make that water safe for humans that make it unsafe for our reefs. Nitrates, phosphates, ammonia, chlorine, flouride and heavy metals. Great for us humans but bad for our reefs.

 

[Nrapp33]

That makes sense.

 

[Gregcoyote]

Always did RO with DI, it makes the purest water. And the additional DI canister and cartridge lasts a pretty long time. I think you would be okay with just RO, but most commercial aquariums use RO/DI.

You don't want good tasting water to add your salt mix to, you want pure water (which tastes horrible).

 

[Gti_Leo]

i wouldn't say it tastes horrible, the DIed water taste lighter and fluffier, but drinking it all the time isn't always good, it removes all the essential like floride that are good for us

 

[kay-bee19]

Kay-Bee,
So how would I find out what additives are in the water.
And regarding the final product of straight RO, ammonia? Please expound on this!

Your city's annual water report should indicate what's added to the water.

While not the primary focus, this article includes information on ammonia which results when the carbon stage breaks the ammonia-chlorine bond of the chloramine and that the ammonia can pass through the RO membrane:
http://reefkeeping.com/issues/2005-05/rhf/index.php

i have a RO unit and it filters down to 1ppm on my tds meter thats good enough for me

I'm probably overly cautious but I change out my DI resin when the RO/DI water registers 1ppm. There's no telling what 1ppm is comprised of. I only use 0ppm RO/DI.

 

[hackteck]

i dont have an ro/di i have an RO so its right where its supposed to be