Another member of the Crew Essentials range is the Crew 3-in-1 Water Meter combining a soil moisture meter, pH and light meter all in one. I nicknamed it the Cheat Meter because it's just that. I'm not talking exact science here though (specialist, super-accurate meters can get very costly, think $100+), so think of this super-affordable tool more as a peace-of-mind back-up for your own common sense, and for checking what you can't reach (like the moisture level down at root level).

I've given it a good go on my jungle and despite it's super affordable price, they do actually work. Sure, they're not crazy accurate, but still a really good guide, especially to check moisture levels down where it really matters to avoid causing root rot. Great for peace of mind to help you avoid over-watering.

PS: No batteries required, the meter itself is like a battery without water. The 2 probes are 2 different types of metal. When you add an electrolyte (the moisture in the soil), it works like a very weak battery, but with enough 'voltage' for the sensor to read. The less water in the soil the less voltage goes through the meter (so you'd get a reading on the moist to dry side). Pop it in and wait 5 minutes for the moisture reading.

How to use:

To check soil moisture
(hydrometer mode) 

Push the switch far left to the MOIST setting. Push the sensors deep enough in the pot to reach the bottom of the plant's root level. Wait a few minutes and the needle will indicate the moisture level. 

Results: There are 3 zones: 1 to 3 is the red zone (dry), 4 to 7 is the green zone (moist), and 8 to 10 is the blue zone (wet). Water according to your plants preferences. Getting multiple readings is normal as water won't be evenly distributed, so take a couple of readings. 

My tests in real life: This is the most helpful setting and the main reason I use this tool. I tested a range of plants, a few I'd recently watered, and it's pretty accurate providing you know how these work. I know they look so simple, but there are still simple things to do (and not do) to get the best readings. I pay attention to the zone on the dial (dry, moist, wet) rather than the exact number. Keep in mind these work on indoor and outdoor plants in a range of soils (more about substrates below), so unless you've got an indoor plant growing in the same high water-holding soil you would use outdoors, you should worry if you get a 'wet' reading on an indoor plants.

I've had it happen lots of times where plants I thought were dry, and would have watered, turned out were still wet down at root level, because these probes go down deeper into the pot than I can possibly test with my finger. I find these super handy if you're not 100% sure and worried about over-watering. I did find the probes need to go down at least 10 to 12cms or more for better readings (the length of the probes is 17.5cms), so if you mainly have plants in small pots, get the shorter Soil Sensor instead.

As a light meter

Move the switch to the middle setting above the word LIGHT. There's a small light sensor panel at the front of the meter. Face that towards the light source in the same spot you plan to put your plant. 

Results: 0 is Dark. From 200 to 1000 indicates low to medium light. 1,000 to 2,000 is the medium to bright zone (direct sunlight registers over 2,000).

My tests in real life: The gauge has a range 0 to 2,000 lux but I found that what I'd call medium light areas still register in the dark zone, likely because this meter is made for both indoor and outdoor use, so allow a bit of leeway with this setting and use it more as a guide.  

As a pH meter

Move to switch to the setting on the right, by the letters PH. Put the sensors quite deep in the soil. Wait a minute or two for the result to show on the pH gauge.

Results: A reading greater than 7 is alkaline, and below 7 is acidic.

My tests in real life: Most of my plants tested the same, between 6 and 7.5, which is the ideal range for indoor plants. Again, I use this primarily for the moisture meter setting, so wasn't expecting amazing accuracy from this or the light settings. Somewhat accurate, and good to alert you if your soil swings too far acidic or alkaline, which can turn nutrients toxic, but there's a reason pH meters cost far more than this meter.  

Want to know more? Here's how a water meter works plus some trouble-shooting do's and don'ts >

Does the substrate type matter?

It may seem obvious after you read how an analog water meter works but the answer is yes, the substrate type matters, because the probes need to measure the water content IN the substrate. All good for the  majority of your standard outdoor and indoor potting mixes, from fine to medium grades, but when you get into very chunky mixes, like larger grade bark-based potting mix, the probes can't break their way INTO the chunks of bark, so will give you a dry reading (because the probes are measuring the air, not the substrate).