For years we used Corning replaceable junction probes in our wastewater samples.  Replacing the junctions every few months gave them longer life.  Unfortunately Corning began manufacturing them out of the country and they weren't as reliable any longer. 

The Accumet flushable junction combo probe (Fisher 13-620-109) was a great replacement at approx. the same price ($150 each).  These probes last a year or so in daily use in various parts of the WW plant.  Sadly I have found that Accumet has discontinued them and only offer one flushable model with a double junction that costs $320 or more. 

Anyone like to nominate their favorite pH probe?  Vital features are:

-Ag/AgCl combination pH probe

-refillable with KCl

-epoxy body

-flushable junction

NOMINATIONS are now open!

I work with many wastewater systems and have the following two flushable junction probes in use at several plants for many years.  I recommend either:

Fischer-Orion 8175BNWP ROSS Sure-Flow pH Electrode, price is in the $300.00 range but well worth the $.  We've had one in service at a site for 10+ years and it has taken real abuse (liquid sludge, industrial effluents, hauler samples) and still performs like a champ.

Another probe facilities have had great luck with is the Hach 51910, however this probe must be used with a Hach sensION meter.