CPVC vs. PVC

Hiya,
I love this place! I've been obsessively reading every day for weeks!

Just a tip: PVC is barred by building codes for use in anything but drains. We should all be using CPVC, or one of the other ones rated for drinking water.
The drinking water plastics costs a little more, and are they tough to find beyond 3" diameters, but you're only looking at $1 per foot in any case.

Peace

CPVC stands for Chlorinated PVC (http://en.wikipedia.org/wiki/Chlorinated_polyvinyl_chloride)which its process is "essentially replacing a portion of the hydrogen in the PVC with chlorine".
As those of us that know about hydroponics, chlorine is an element you'd rather not have present. You should really do some research before making such a statement, especially when it is detrimental to the application.

The difference between polyvinyl choride pipe (PVC) and chlorinated polyvinyl chloride (CPVC) pipe is an additional manufacturing step. My understanding is that the reaction that produces PVC still has some reactive sites from the original polymerization that formed it. The CPVC is treated with free radical chlorination, which caps the remaining, reactive sites. CPVC doesn't leach toxics, and is used for drinking water and applications requiring less reactivity (temperature resistance, inert to more rigorous chemicals , etc).
PVC itself is quite unreactive, but because of the nature of polymerizations, whatever leaches off is going to glom onto you. That's why it is against building code for drinking water, but not waste water: The concern is low level, but long term.

one thing you might need to consider is that CPVC doesn't have as high of a pressure rating as PVC. I doubt PVC would hurt your plants too much, as I've seen grows with PVC used work out fine.

It takes equipment that costs tens of thousands of dollars to detect the very, very minimal leaching of anything in PVC pipe. The real scare of PVC is with infants not adults. PVC for all but baby bottles that are heated with milk inside before given to a baby are grossly over blown. It is pretty much guaranteed that the minute amounts of heavy metals and such that are present in yout fertilizers and growing media is a greater threat to your health than and leaching from PVC pipe used in your nutrient delivery system or aero tubes.

Considering probably 90% of the agriculatural products grown in this country are grown in fields fertilized with the same bulk fertilizer ingrediants used to make our nutrient formulations what difference will a small bit more trace contaminants make.

About the only real gain you would have using CPVC over PVC is with Nitric acid or Phosphoric acid and not many small growers use those acids full strength in pH anlyzer/controller sytems so PVC is really seldom an issue there. Even then CPVC is not really much better an option than PVC. Neither, by choice, would be used in industry for highly acid or highly alkaline, only by necessity due to the higher costs of a better wetted materials such as PFA Teflon.

Cool! Thanks for the reality check, Fatman. I just got caught up in the righteous horror the guy at the hardware store had when I talked to him about piping my house with PVC. I did more reading after that post, and couldn't find much of any justification for the Ohio code about it.