It's not really a cleaning thing, but I think all fishkeepers should have a few 1 or 2 litre margarine/ice cream containers hanging around.
They can have holes cut in them for emergency fry/breeder/sick bay containers.
They're great for catching fry and fish like plecs and loaches that can get tangled in nets. Even for other fish being moved from tank to tank, you can catch them in a net and use the margarine tub to keep them in water while you carry them round the house.
You can scoop up substrate, either for changing it or for setting up fry tanks, or for adding sand or gravel to an already set-up tank
If you need bare bottomed tanks for fry or breeding, you can grow plants in them.
You can use them for holding mosquito larvae while your kids fish them out of the water butt
A multidude of uses and they're food grade, so totally safe
They can have holes cut in them for emergency fry/breeder/sick bay containers.
They're great for catching fry and fish like plecs and loaches that can get tangled in nets. Even for other fish being moved from tank to tank, you can catch them in a net and use the margarine tub to keep them in water while you carry them round the house.
You can scoop up substrate, either for changing it or for setting up fry tanks, or for adding sand or gravel to an already set-up tank
If you need bare bottomed tanks for fry or breeding, you can grow plants in them.
You can use them for holding mosquito larvae while your kids fish them out of the water butt
A multidude of uses and they're food grade, so totally safe