Question: freshwater aquariums

Question: freshwater aquariums

One of my other hobbies is keeping two freshwater aquariums. When I do a partial water change, it feels like such a waste to put the water down the sink. So. I know that aquarium plants like nitrates, but what about my flowers? - The fish are betta, tetras and cory cats (corydoras catfish) - They are all fed Hikari foods (micro pellets, bio betta gold and algae wafers) - There is NO salt added to the water, though I do use a water conditioner (Tetra AquaSafe) The pH level hovers around 8.0 (our water here is very basic), the aquarium is fully cycled (ammonia and nitrites are at 0 ppm) and the nitrites are at about 20 ppm. I mostly grow roses and veggies, but I doubt I'd use it on the veggie garden for fear of chemical contamination. So guys, what do you think?
Dahlias Blooming! Long Entry (sorry gardening gets me excited lately)

Dahlias Blooming! Long Entry (sorry gardening gets me excited lately)

Some tips please

Some tips please

Ivy Monster

Ivy Monster

New piece….

New piece….

Jerusalem artichoke

Jerusalem artichoke

Identification

Identification