Re: RO unit

[IDMiamiBob@aol.com]

Micheal writes:

> Can someone give me the run down on RO vs Deionized?  I am contemplating
>  purchasing an RO unit from Debron Aquatics.  They have a 50 gallon/day TFC
>  for $160 or a Maxima 50/day for $230.  Are these good prices?  The Maxima
>  has a deionization cart. attached, is it worth the extra $70? Thanks for
>  any imput. I want to make my purchase within the next few days.

RO, or reverse osmosis operates by forcing water through a membrane that is 
selectively permeable only to water.  It isn't perfect, but darn near.  Water 
purity is very high.  The two biggest drawbacks are that the membrane is 
somewhat delicate, and you discharge a certain amount of "waste water", which 
contains all the stuff that didn't go through the membrane.  If you lived in 
a semi-arid, or arid location, like most Western US states (including 
southern CA) I don't consider this an environmentally responsible option, 
unless you find some way to utilize the waste water.  Some folks in LA don't 
seem to care that one of  the hugest civil engineering projects ever 
undertaken was the diversion of the vast majority of the Colorado River to 
fill their growing demands.  They further don't care that they can't keep 
stealing water from everyone else around, because we want some, too.  And for 
that matter so do the fish, birds, lizards, etc.

De-Ionization uses specially selected chemicals, usually refered to as 
resins, to replace all positive metallic ions, such as Ca++, Na+, Mg++, etc, 
with an appropriate number of H+ ions.  Then it also replaces negative ions, 
such as CO3 --, Cl -, PO4 --, etc with OH- ions.  The replaced ions are 
trapped in the resins, and the H+ and OH-ions join up to form H2O.  Its 
biggest drawback is that you have to replace or recharge the ions 
periodically.  It has no waste water discharge, and is therefore more 
environmentally friendly in dry climes.

RO maintenance is generally simpler, but DI costs less for the water you use. 
 The cost of recharging ions is about the same per gallon as the cost of 
replacing the membrane and other stuff.  The DI recharging chemicals are 
somewhat dangerous, but the safe handling procedures are easy to learn and 
follow.  You should be comfortable with them, or replace the resins as needed.

DI only removes stuff that is in ionic solution.  RO gets other stuff as 
well, but it isn't perfect at getting all the ionic stuff.  That's why some 
RO units have DI afterwards.

Some products sold as de-ionizers are actually just water softeners.  The 
replace hard ions, like Ca++ with Na+, but don't really achieve the end you 
are looking for.  Question everything.

In Kentucky, you don't currently have a water shortage, nor are you likely to 
soon.  I would say the choice of RO or DI is pretty much up to you.  The 
output products and cost of operation long-term are about equal.  Again, when 
you go to the store to get it, question everything.

Bob Dixon


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