Bluelab Combo Meter Plus with ProbeIt's all you need for simple and reliable crop management Details Help Your Plants Grow Fast, reliable and versatile: Combo Meter Plus means you will be able to measure more and build a better understanding of your complete growing system. The multimedia Leap pH probe can be used to measure nutrient solution and directly in the rootzone in a range of growing substrates including soil, rockwool, coco coir and peat. Plant Health in the Palm of Your Hand