Another set of RO filter clarfication questions...

I read somewhere while researching RO filters that you can DAMAGE your pH pen/probe with RO water? Is that correct? I read on later and it sounds like it's partially true... if you pH the RO water itself directly you can't get a reliable reading (from someone calling and asking HydroLogic - thread on this forum)... they advised taking a pH reading after adding Ca/Mg or nutes in general... something about not having enough ions or something to get a reading.

1st question... Can I damage my $$$ BlueLab combo meter doing this? If I'm following things correctly it's the DI (DeIonization) that causes this... hence why someone suggested bypassing the DI stage on one of the reccomended units...

I also know that RO will strip out the Ca/Mg and you need to add that back in (small amount per the additive's directions)... But... I found a filter that seems to be directly targeting that issue... As sometimes "Drinking Water RO Systems" do...

http://www.theperfectwater.com/Tap-...-Reverse-Osmosis-Water-Filtration-System.html

2nd question... Is this BS? Am I better off still using Ca/Mg additives versus their solution (or for that matter any RO system that claims to be for "drinking" water which implies adding Ca/Mg back in to the final water output)...

I had also read that the difference between Distilled Water and Drinking Water at your local grocery is that the Drinking Water has had minerals (Ca I believe - not sure about Mg) added back in for taste since RO water tastes like crap to folks...

3rd question... So until I get things going with a RO filter system - should I be buying Distilled or Drinking water? If I get drinking water (seems to be available in larger sizes like 5gal more so than distilled) what additive if any is needed? If they are only adding Ca back in, it sounds like I need to go with a Mg only additive (Epsom salt?)...

Thanks RIU! I should have a good setup started once I address this...

never heard of r/o water damaging a pen, but, it could be possible. Yes, it's true, r/o has no buffers, so p.hing it straight won't get you anywhere.
I buy these units
http://www.purewaterclub.com/catalog/product_info.php?cPath=67&products_id=264 no D.I

adding cal/mag occasionally would be cheaper. Until you get a unit, just let your tap sit out for 24 hrs, it will be fine. I never recommend using distilled.

I guess the key here is whether my local water company uses Chlorine or Chloramines... Since chloramines aren't removed from just letting water sit out - from my understanding.

If Chlorine, then yeah... that's what I had been doing before the last 3 changes which I've done with store-bought Distilled water... I only need 6 gal. at a time - for now...

I heard bad things about using distilled water for plants because its so mineral deficient it actually sucks it out of the plant