LOL I remember the days before HOB
filters were invented. All we had was the little plastic boxes that went inside the tank that you filled with glass wool and loose charcoal, hooked up an air line to and the bubbles rising out of the vertical exhaust tube would pull water through the filter. The flow was so inefficient unless you had so much air going through it that it looked like an air gieser in your tank.
Also remember the only fish food was a corn meal like crud made by Wardleys that clouded your water no matter how little you used. LOL. Also metal framed tanks with slate bottoms and black petroleum based glue sealing them. Oh Jeees! We've come a LONG WAY since then. Now you know why I call myself "Old Scales". Hee Hee.