Water Quality Meter

Around two months ago, George Hatfield of Hatfield Orchids strongly suggested to the participants of the International Cymbidium Alliance, an online discussion forum, the purchase of a water quality meter that measures pH and total dissolved solids (TDS), for reasons of achieving better control over the pH of the fertilizing solution to maximize uptake from the orchid roots, as well as to avoid using media that has excessive salt content, e.g. coconut chips that still have significant salt content after washing and leaching.

I didn't run out to buy a meter at that point in time. But, I did observe during the weekend I was "led astray" that other serious orchid growers also used water quality meters as part of their orchid husbandry practice. The sum of these observations and suggestions motivated me enough to finally buy one (see below).





























Here are the probe pH and TDS values for the calibration solutions.




























Here are the pH and TDS values for distilled water.




























Here are the pH and TDS values for my rainwater that I use to water my orchids. I expect the rainwater values will change according to the seasons, e.g. pollen content in Spring.




























While I'm now ready to use the water meter when I make up my fertilizers, I also need to re-evaluate the advice of different orchid growers regarding the amount of "growth" and "bloom" fertilizers when the N, P or K values are given in ppm units. I've been accustomed to tsp/gal units, not ppm/gal units. I don't expect the results for using the water meter will be available for some time, but I'll be keeping notes...