A number of inexpensive pen-like instruments are available which can be used in the greenhouse for assessing pH and soluble salts.
Pens are available from most greenhouse, agricultural, and forestry supply houses.
Proper use of these instruments provides accurate pH and EC measurements which a grower can use to make immediate crop management decisions or to seek further in-depth testing by a commercial soil test lab. The objectives of this fact sheet are to discuss the equipment and supplies needed to maintain and use the pens. In addition to the pens the following items are needed to take care of the pens and to do pH and EC tests. Many of the items can be obtained for free from home or inexpensively from the grocery store. Of course more expensive and professional looking supplies can be purchased from a science lab supply company, but the tests won't turn out any better than using the cheaper alternatives.