Hi, buddy!
My opinion, try gravel. some BB resides in them. Or if you really don't like gravel, try sand. its better coz u wont have to siphon it much... and you've got (a) bichir/s. be careful when moving rocks.
weekly 10 to 25% WC is good. remove water via siphon so you can suck out the stool at the same time. (I also net out stool sometimes when i see them floating around the tank floor.)
The magnetic thing is nice and convenient though not really a necessity. i do my glass cleaning either with a sponge and a stick or a sponge and an arm. (do this right before your weekly WC so as not to cause too much stress on your babies). The razor blade, you'll use for scraping/chipping off calcium build-ups(white stuff usually seen at the dry, upper part of your glass) but i think you need not worry about this now if your tank is new. In a few months maybe. Its not even very visible when its wet.
note: You don't really need visual evidence (smudge on glass, stool on floor, etc.) to perform this task weekly. it's a preventive measure to keep them healthy and disease-free.
It's also a lot easier than trying to cure/medicate sick fishes.
Good luck on your weekly chore! lol ! hope your fishes stay healthy, man.
btw, what fishes do you have in this tank?
