PH monitors

Dear folks, 
		I'm interested in utilizing  CO2 fertilization in most or 
all of my six tanks.  What I'd like advise on is the usefulness of PH 
meters, specifically the one advertized by Sandpoint.  Do people find 
them uselful?, can you use them to check the PH of different tanks in 
succession or are they set up on one and need to remain there.  Do  
people recommend Sandpoint or is there a better idea.  Like I said, I'd 
like to use CO2 fertilization but I also want to keep a close eye on the 
PH swings in order to keep them to a minimum.  The current dye based test 
kits show green for neutral, yellow for acidic and blue for alkaline.  
I'm looking for something a little more precise.  
					Thanks in advance,

						Miles Morrissey
						Easthampton, MA USA
						mmorriss at sophia_smith.edu