I have a few question about Aqua-Tech filter Cartridges for my 10 gallon tank?
1) When I'm changing out the old filter cartridge should I soak the new filter cartridge in tank water or, sink water?
2) How often do I REALLY need to change the filter cartridge?
3) Why doesn't the Bio-Fiber have to ever been changed,
yes.
Only when you see the filter performance is going down. And at that point you can soak the old filter in dirty tank water and scrape the crud off the edges off.
You want to preserve the filter's bacteria by switching