All you young guys and these abbreviations
This is true, my hermit crabs have canker sores older than most people on here.
I first used a UG filter with 4 uplifts and a 4 outlet air pump that vibrated so much your teeth's fillings would fall out and mirrors and photographs would fall off the wall the neighbours would ask me to stop constantly drilling the walls.
When I started there was no vibrating pumps, there was only piston pumps with leather pistons that you had to oil. The oil would get in the water and make a realistic Exxon oil spill.
https://www.reef2reef.com/ams/how-i-got-started-in-the-hobby-in-1971.177/