Easy way to monitor levels in the soil

We picked up this soil meter for the plant in our kitchen window because we can never tell when we need to water it. It seems like the soil is okay, but it is hard to tell if it is truly wet enough or whether we need to add more water. It has a lot of greenery on top making it hard to see the soil underneath. This monitor has helped us know when to water it without over watering and having things spill out the bottom or rotting the roots from the inside.   This monitor has two metal prongs that go in to the soil while the monitor sits on top and displays not only the moisture levels, but also the pH level and light level. I am honestly not sure how to tell what the light level measures, though. The plant is sitting in the window, so gets ample sunlight, but when the setting is on the light option, it doesn't seem to make any changes, even at night when there is no light to measure.   The pH monitoring and water moisture monitors work great though. Simply by flipping the switch, we can easily identify the levels of either. I can now visually track either level and make adjustments to my plant as needed. And the device uses no batteries. I have no clue how it works without using batteries or power of any sort, but it does. And it seems to be accurate. After a few days of using it, we have been able to keep the plant hydrated and it is thriving already! I am super impressed!   Definitely something I am glad to have and would pick up again in a heartbeat. I am loving the readouts and knowing how best to take care of my plant. I was overwatering it big time before getting this, though the top of the soil seemed dry and I thought it was time again. Not any more!