The Puffer Forum

Nitrification bacteria will not be removed by stirring substrate - they may get buried below the oxygenated zone and die, but alive they will not be removed by stirring. Fluidized bed filters, including sand-substrate ones, do work and the bacteria survive 24/7 stirring quite well.

But raising the SG too quick could cause problems.

nothing to measure just a general proportion calculation. 1 Tbsp for every 5 gallons of water