Review on 🔬 Hanna Instruments HI721 Portable Colorimeter by Bobby Plymell

The box was opened immediately even though there were enough reagent packs. Not sure if it was a demo model or something like that. It's almost impossible to get everything in one bottle, it's not clear how important it is to make sure every grain gets there. I'll look at a little mini funnel or something. You can't follow the directions and use a bottle, run it as C1, THEN mix the reagent. The device switches off automatically before this time and aborts the test. You should have one bottle with unreacted sample and another with reagent already added ready to use. So far I've gotten 0.00ppm in almost every test, which seems lazy. I tested from the faucet and from my tank to which I added iron supplementation daily. I added a few drops of the supplement to one of the bottles and mixed it up with a tap to make sure it was really working and it gave me the ppm. Yesterday I tested the water in the aquarium and got 0.33 parts per million. Which seemed plausible, even though I added less iron than the night before. Then I ran the test again on the same samples no more than 2 minutes later and it read 0.00ppm. I just don't believe in this stuff yet. It seems very convenient, but it doesn't seem accurate yet.