"Rule #99 (or something like that): There's a reason why test kits from Salifert are $25 a piece and they don't sell an "all in one" test kit: They WORK. The only thing worse than the all-in-one kits is a swing arm hydrometer. So, go ahead and throw that away too. ;-) ("Swing-arm hydrometers don't work is Rule #5 - or something like that - they are singularly responsible for more tank crashes than any other instrument - they gradually fail over time). "

What do u recommend for reading SG?