filter aquarium water

I swear every time I try to help my fish, I end up hurting them. I just learned that you shouldn't change the water the same day you clean the filter. Because it's too much change for them to take. If this is true, I'm going to lose every fish in the tank. I learned that you're not supposed to...

Hi, although I am still new this hobby and my aquarium 70l (19 gallon) tropical aquarium is mid cycle, I am putting thought into getting a new filter. I currently have the juwel bioflow one which is quite bulky, has poor surface agitation and only allows for regular mechanical filtration (no...

I plan on purchasing a 29 gallon tank tomorrow and need help on picking a filter for my tank! I’ve heard a lot about the marine land filters but I’m not sure which filters are the best for a 29 gallon. I plan to have around 15 ish fish in this tank. Thank you.

... Or can you simply clean the filter in a bucket of dechlorinated water? This means you don't have to drain any water from the tank.