Short answer: strips or drops are enough for most Kratky growers, because you mainly check pH at mixing time. A meter is more precise and easier to read, but it needs regular calibration and care.
Test strips
- Pros: cheap, simple, nothing to calibrate
- Cons: colors can be hard to read precisely, and some strips are not designed for the narrow range hydroponics needs
- Best for: occasional checks and growers starting out
Liquid drop kits
- Pros: inexpensive; many are made for hydroponics and cover the useful range clearly; often easier to read than strips
- Cons: still a color match, so precision is limited; the indicator runs out and expires
- Best for: most home Kratky growers
Digital pH meters
- Pros: precise numeric reading; fast once set up
- Cons: must be calibrated with buffer solutions, commonly pH 4 and pH 7 (Oklahoma State University Extension); probes must be kept moist and eventually wear out
- Best for: growers mixing often or chasing a specific problem
Accuracy only if maintained
An uncalibrated meter can be further off than a fresh drop kit. If you buy a meter, buy calibration buffers and probe storage solution with it, and follow the maker’s care instructions.
A practical approach
Start with a drop kit or good strips. If you find yourself testing often, or your readings and plant symptoms do not add up, a meter is a worthwhile upgrade.
Related guide: supplies for Kratky nutrient solution.
Sources
- Dunn, B. and Singh, H. Oklahoma State University Extension. Electrical Conductivity and pH Guide for Hydroponics (HLA-6722).
