Good questions and one I am working on for a sicky of my own.

I think the water we use to give to our plants is highly underrated.

A lot of people have varying opinions and to each his own.

My opinion....

The kind of water you use is critical to the plant on an indoor soil grow. In the wild, you have natural erosion, breakdown of foilage, bacterial colonies and an entirely private ecosystem working on the soils and water.

Tap water, at least in the US is some of the filthiest water in the civilized world. It contains many elements not found in any water naturally and the required chemicals we need to put in there can kill the water.

Kill the water?

Yes.

If looked at under an electron microscope, a fully funtioning water molecule is shaped much like an octangon. However, after treament, use, recycling and so forth, adding flouride (which no plant likes or uses) etc....the same molecule will be missing 'links' or sides of the 'octogon' shape.

I wont delve into that too much further yet, as a new grow I am using will test some theories I have planned and a machine I invested in to return the water to a 'pre-historic' state....ie....the way water was before even dinosaurs ruled the earth.

A new SOG grow will show the results of some testing...stay tuned...

As for you hard water issues, mineral will affect the alkalinity to a degree, but no, there is no direct comparison between them being the same thing.

Alkalinity is the "pH" value of water, with 7.0 being neither acidic or alkaline in nature.

The higher the pH, the higher the alkalinity and vica-versa.

Hard city water can suck.

You should look into your grocery store....many of them now sell distilled water (which is really de-mineralized water) by the 5 gallon jug for 25cents a gallon. You gotta haul the fuckers around in a cart, but they are out there much cheaper than bottled water.

I would definately look into getting some other water. Yes, you can grow with hard city water, but I suspect its far more important than I have seen discussed and will be one of the major tests I conduct on a new SOG grow.

Hope I was general enuff andd left myself a way out...