Waterproof work fine as long as you calibrate it +/-ph. depending on your substrate and grow-system can effect your ph. A healthy soil substrate for example will help to balance it out. More accurate measuring is required with hydro systems.
Accuracy should be the first consideration. You have to know where your at before you can get to where you want to be. The best (and very expensive!) meters have an accuracy of ±0.002 pH units. Hanna® makes excellent probe meters and in scense get what you pay for. Other manufactures like ExStik® & Oakton® make affordable water-proof pens.
Hanna WaterProof EC/TDS & Extech Waterproof ExStik pH Meter - PH100 meters seem the top sellers. These are both 100% waterproof & easy to read digital display. Priced from around $100.
The new waterproof 50-HI98129 & 50-HI98130 Combo testers from Hanna are designed for high accuracy pH, EC/TDS and temperature measurements. No more switching meters to measure the pH and then the EC or TDS of a solution. At startup, Combo performs a self check then displays the remaining battery level to assure proper working condition. These testers also have a stability indicator and hold feature to prompt the user when to take the reading & freeze the display for easy and accurate recording. Calibration and temperature compensation is automatic, while the EC / TDS conversion factor and temperature coefficient factor (ß) are user adjustable for application specific measurements. For calibration in pH, the user may choose between standard or N.I.S.T. buffer sets.
Model: 50-HI98129; EC - 0 to 3999 µS/cm; TDS - 0 to 2000 ppm
Model: 50-HI98130; EC - 0.00 to 20.00 mS/cm; TDS - 0.00 to 10.00 ppt
