Di/distilled Water

[jhnrb]

A SHORT ARTICLE ON DI AND DISTILLED WATER

Info on DI and Distilled Water

From an analytical standpoint, there is a huge difference between distilled and deionized. There are different degrees of deionization depending on the application. Most instrumental analytical applications cannot use distilled water. However, distilled water is usually used in deionization units, which prolongs the life of the filter beds.

There are many measures which will tell you something about the purity of the sample your looking at, i.e. index of refraction, conductivity, standard reference comparison etc. etc.

Siemens are a measure of electrical conductance, and therefore, only take into account polar impurities. This is the general convention used in determining the purity of water (measured as resistance). Luckily most if not all of the substances which make it through distillation (boiling point less than water, and generally nonpolar) will be trapped early on in the water purifier (carbon beds). The remaining ions are removed in the ion exchange resin beds.

So what impact does this have on our tanks. Well, that depends on what you started with, and how efficient the distillation was. I would guess, there wouldn't be much difference between distilled and deionized, other than a lot of low molecular weight mostly nonpolar molecules, and ions which are either distilled first, or carried over. However, when you take into account that we aren't dealing with true ecosystems, and the whole system of checks and balances is out of whack, very minute quantities of impurities can cause major changes in the balance we are all trying to reach. As anyone who has had a diatom bloom knows.

The smaller the tank, the more important it is to always use deionized water. In larger tanks, during cycling and such, you can clean up ordinary water, and then later on, doing changes with a lower quality water will have less of an impact (solution to pollution is dilution). In small tanks, you don't ever have that luxury.
--------------------------------------------------------------------------

DC wrote:

DI - 0.05 to 0.06 microsiemens

Cold Sterilization - 0.5 to 0.7 microsiemens

RO - 10 to 15 microsiemens

These were posted by Eddie Tsang.

Looks like the rundown on distillation is this;
-stainless steel distillation: 3-4 (uS/cm)
-glass distillation: ~1.5 (uS/cm)
(couldnt make the cool little micro symbol on my keyboard so the u will have to do)