What is Reddit's opinion of HM Digital PH-200 Waterproof pH Meter, 0-14.00 pH Range, 0.01 pH Resolution, +/- 0.02 pH Readout Accuracy?

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This is what I use: https://www.amazon.com/dp/B00132G102/

Get a big bottle of the General Hydroponics pH 7.0 calibration and storage solution. You need to rinse the electrode with clean water after every use and change the storage solution regularly (1-2 weeks), but if you keep up with the maintenance they'll stay accurate and last quite awhile.

Those drops suck IMO, same with the strips. I feel that the nutrient ions somehow interfere with the reaction on the strips, and you get color interference like you said with the drops. A glass electrode pH meter is what you want.

Proper pH is fundamental to the plant thriving just like light, temperature, humidity, etc. because it's so closely tied to root health and nutrient absorption. It's worth paying close attention to.

https://www.amazon.com/HM-Digital-PH-200-Waterproof-Temperature/dp/B00132G102

They work great, and I'd really suggest getting one for hydroponic grows. I use an HM Digital pH-200 which is nice because it comes with a replaceable electrode, so when it wears out or breaks don't have to replace the entire meter. You also will need some pH 7.0 calibration/electrode storage solution as the meter will drift, so calibrate weekly. This meter is on the expensive side of pH meters for hydroponics, but I believe in the "buy it right, buy it once" mantra. Sure you can buy a meter for $40 but you'll end up buying it twice after the first one breaks/malfunctions/whatever, so just get the nicer one and be done with it.