Rather than pouring away old aquarium water, you could use it as free plant feed
The problem
Houseplants need liquid fertiliser, but this can be expensive. Fish tank owners, meanwhile, produce litres of nutrient-rich water during water changes, which then gets poured away. Could it feed houseplants instead?
The hack
Water from a freshwater aquarium contains nitrogen, phosphorus and beneficial bacteria. Rather than discarding it during routine water changes, use it to water your houseplants, giving them a free feed.