If the Nitrite level in your system is right, then the PH has to be right.  However, if you only check PH, your Nitrite Level can still be off and you can still have a serious corrosion problem.  This test is far more important than a PH test.

What about pH?

We at Wood Boiler Solutions, LLC are career professionals in the field of industrial water treatment and look to provide solutions to the wood boiler owner and industry alike.  The question of "What about pH?" comes up all the time.  Many have been told it is a sole indicator of system protection.  Ask any professional in water treatment if they were to service a 5000 gallon low temp hot water (boiler) loop if they would stake their program effectiveness on a pH test alone and they would say no.  Ask the same professional about a 300 gallon system (like our wood boilers) and they would say no.  But maybe a better testimony for the need,as an industry, to get "beyond" the pH test alone is a summary of a recent phone call to our office (one of many):  Caller indicates they have a 150 gallon wood boiler by "Brand X" manufacturer.  The unit is two years old.   The caller indicates they fire it year round and have to add water to it about once a month or so.  In addition they had leaking problems where they lost a good portion of the system water.  The caller indicates "Yeah I have added a lot of water to the boiler over the last two years".   We then ask the details of their chemical program.  "I added what they sold me when I bought the boiler".  We ask if they have added since.  "No, they (Brand X manufacturer) check my pH once a year and it always checks good".  "In fact I checked it myself just a bit ago and it still checks OK".  "That is why I called you guys".  The caller goes further to say "Because I KNOW there can't be anymore chemical left in the boiler from the leaking alone". Here is another analogy:  Customer calls the local pool supply store to question his results with his swimming pool.  "My pool is green but the pH strip is right at 7.6 like it says it should be".   Further he says" I added chlorine when I started up".  The pool shop asks "What is your free chlorine level at now?".    The customer replies "I don't know-I don't check that." Another:  Our facility (WBS) has water with a pH of 8.67 straight out of the tap.  What does this mean in regards to the inhibitor level that we drink every day? All good inhibitor formulations need alkaline (raise pH) donors to stabilize and enhance the product in one way or another but this is not all that plays out with inhibiting corrosion. pH is viable to monitor if : it is combined with other measurable parameters of water treatment testing, and the knowledge necessary to comparatively interpret its given measured value is known. Measuring the pH of the condensate that forms inside the top of the water jacket in an open system (air space above the water line) IS something that is worth measuring and monitoring.  Low pH condensate (below +/-7.5) is aggressive and will tear apart the top of a boiler in a short time.  Condensate naturally occurs aggressive (low pH) because it is a combo of CO2 and H2O, which forms carbonic acid.  How aggressive your condensate will be depends mainly on two things:  1) The chemistry of the water you fill your boiler with.  The more raw material for making CO2 (m alkalinity) in the fill water the more carbonic acid produced.  That is why one customer may have great luck with brand X boiler and the next guy a state over will chew an unwanted roof vent in a season or two.  Don't necessarily blame the boiler-look at the water!  2) The second being whether your chemical brand contains the necessary additives needed to neutralize the CO2, condensate cycle. Treatment Solution 101 is completely, accurately, and directly measureable everytime with a simple test.  pH is an important element to system treatment but is not a viable sole indicator.  Complimentary but not independent. Our mission statement is to empower the wood boiler owner with sound knowledge and quality products.