Yes we use these all the time and have a class set. We used then on a regular basis for CO2 gas and probably 4 times per year for dissolved. So we only purchased 5 sleeves for our sensors. They are so easy to use and have very good repeatable results. If you have the cash, a good investment. You run them through Sparkview which is free downloadable software from Ciderhouse or the Pasco website. I have not heard a bad thing about them as yet and many schools we interact with use them.
