Distilled water??

What's the difference between distilled and RO water? I was under the impression they were the same but the dude at the grow shop told me too definatly not give my clones distilled water because it contained too much sodium? I thought the point of distillation was to remove impurities, what gives? Mr. Green from the video series gives his clones distilled water. I thought this was a good idea because distilled water has such a low ppm combined with a slightly acidic nature, perfect for clones? or not?

The guy is a dumb ass and is likely confusing water run through a common water softener with distilled water. A water softener is a filter with resins beads that is caharged with sodium chloride (salt). It there for electrinically attracks calcium ions when they water comes in contact with the charged beads. This means the beads exchange sodium for the calcium. Ie the water gains sodium and loses calcium. A distiller is a vessel where the water is heated to a vapor. The vapor rises and is sent to a side arm where it is cooled and becomes a water that is collected. If careful control is done a water that is neraly pure is collected. This usually not the case as precise cotrol is not maintained so the distiller passs impurities (chemicals) that evaporate at lower temps then water and when the water is over heated it carries salts and such due to turbulence foaming etc. It is much better than hard tap water but typically worse than RO water. However distilled water typically has a TDS of only 5 to 50 ppm. For top of the line water: first run the water through a water softener, then prefilters, then an RO filter and finally through a good mixed resin DI filter or two. That is gross over kill for pot growing water however. For most peole filtration of heated water is mot re than adequate. If they would rather spend money than effort then a RO filter works real well.