Looking for which types of plants would work best for my two koi 75 gallon tanks to help lower nitrates.

My problem might be that the tanks are in the living room and I like the water level high so the light doesn't overwhelm the room so a hanging light wouldn't work unless I block out the sides. I have a small led light strip in both tanks that just clip under the tank lids, it has white and blue lights.

I have Caribsea Crystal River aquarium sand and don't want to change the bottom gravel.

I would like to get rid of the artificial in the tank and go will live plants but think the koi fish would destroy them so maybe floating plants that don't grow to tall or get really messy would work better but I guess I would have to upgrade the lights one way or another?