i agree about the DO test, i think hes jsut a big dork and had to have the whole series, and that why he got it. he uses it on our 135 tank but i dont think he ever tests customers DO, if he does im sure he knows to get a fresh sample, hopefully. IMO, dissolved oxygen isnt muct to wory about, especially if you have decent circulation, and lots of algae in the tank.
oh well, hes a retired probation officer, who has beehives, makes soap with my mom, and takes care of our 135 gallon tank, so it gives him somethign to do!
good luck
jon