I’ve used a bunch of different meters over the years and have come to one conclusion. Trash. When a bunch of replacement Bluelab Guardian probes were bad brand new, I threw it all away. They’ll lie (even after calibration) after about 6 months to a year. Test drops have never failed me. Thankfully I’ve always had them to test against digital meters.

5 years? I don’t believe that at all. They don’t last more than a year even if maintained properly. It’s lying to you at this point.

NEVER buy a digital pH meter. NEVER. Throw that shit in the trash and use test drops.

Hydro is too delicate for seedlings for most new growers. Better know what you’re doing. There will be no forgiveness. Coco and soils are forgiving. They create a buffer. Water temp and pH better be on point 24 hours a day or you’ll run into serious problems.