A LOOK BACK at WATER CHEMISTRY

A few days ago I came across a 1950s pamphlet about aquarium water chemistry. The publisher was considered THE authority on aquariums, but the pamphlet never mentioned the nitrogen cycle, and some aquarists were unaware of it until fairly recently. I count myself among the formerly uninformed. The hobby has really changed in the last few decades, and fish keeping endeavours now tend to be much more successful.