I have used a Truncheon year around for 15 years. It has been dropped in a nutrient tank several times. Except for changing batteries every 5 years, I have done nothing else to it, and it has never failed to work correctly.

Norm

Thanks for your advice. Just picked up a bluelab Truncheon today, and it works great. Interesting to find out there are several different ppm scales in use, with the x500 and x700 being the most common. I also notice many web sources dont differentiate between the two. Guess I should rely on the CF and EC instead.

It's been mentioned in a couple other threads, so sorry if you've already read this: PPM is never measured. The only thing measured is EC. Some of us still can't figure out why there seems to be a desire to switch EC to a ratio of ppm, which is essentially pointless. The 500 and 700 scales simply mean you take the EC measurement and multiply by 500 or 700 to come up with a crude approximation of ppm of dissolved solids. That doesn't even mean that those solids are fertilizer (though they likely are). The only number that matters is the EC value. The rest depends on your ability/willingness to follow the directions on a manufacturers label. I don't. I use less than GH recommends, just in the same proportions.

I also just ordered a bluelab Truncheon meter. If it last as long as other's have, it will be worth it.