I was going thru some of my aquarium reference books that I've accumulated over the years and came across 1 I thought was pretty interesting. "The Marine Fish & Invert Reef Aquarium" by Albert J Thiel (printed in 1990) was the "bible" when I 1st started reefkeeping. Suprisingly not much has changed in 20 years, or at least not as much as you would think.
The biggest changes are in biological filtration and alkalinity. Back then, before someone thought of using live rock in your sump, bioballs (and lots of them) were the way to go. I followed this method successfully for about 15 yrs till I made a bigger sump and used lr
instead of the bioballs. The other very interesting change was the recommended alkalinity level. Back then, and obviously before there was success in keeping SPS
corals, you were looking at alk
in the 12dKH to 18dKH level.
The basics of reefkeeping haven't really changed much in 20 yrs. The biggest changes are in lighting and chemical filtration. The requirements haven't changed, it's just alot easier to provide them now.