ROX 0.8 2/3 cup. Replace monthly.

I use Kent, want to try the Zeovit, but it is always on back order. Kent has worked fine for me.

1 litre for 180G display and 105 G refuge - actual water volume is less

I replace once a month

I would guesstamate about 225G of water

box from Aquagiant (~2cups) placed in mesh bag in high flow area of sump, try to remember to change monthly, 200g system.

Kent. 2 cups in a TLF changed monthly/when I remember.

150ish gallon system

No particular brand. whatever I can find cheap.
I've tried SeaChem Matrix, Kent, and currently on a can of Marineland.
Only difference I've noticed is price. so I gave up and just buy the cheapest one.
A little extra dust isn't a big deal, just rince it longer.

Use 1.5-2 cups along with a cup of purigen (separate bags) inside an eheim 2213 cannister.

Change every month or 2.