Many freshwater aquarists have a basic understanding of beneficial bacteria, aerobic bacteria turning organize waste -> ammonia -> nitrites -> nitrates, and anaerobic bacteria turning nitrates -> nitrogen gas.
But I'd like to really truly understand what's going on in there, the chemistry behind it. How pH, GH
all play a role, difference between ammonia and ammonium, the chemistry behind the molecules of the formulas for ammonia/nitrites/nitrates, the chemistry behind testing kits (the WHY's behind needing to shake the nitrate bottle for so long), etc. etc.
Outside of the normal "this is what a cycle is" bits, what are some fantastic resources you've come upon that provides in-depth education on the chemistry inside a freshwater aquarium?