Plants to lower nitrate level?

I have a 10 gallon (that is probably overstocked). I have 1 small red honey gourami, 4 different kinds of cory catfish, 2 pygmy cories, 2 nerites (my cleaning crew), 1 assassin snail that I've had for like 4 years and will never die, and 1 rabbit snail. I used to have many of them (except for the gourami) in a 20 gallon and things were perfect, but I had to downsize when I moved. I got the gourami in February of last year.

I syphon and change the water 2x a week and add new purigen or filter media once every 5-6 weeks. I scrub the sides when I see algae, I prune plants, I mean I do everything I can think of. Whenever I test the tank over the past year, everything is fine except for the stupid nitrates. They've never been the darkest red color but somewhere reddish around 40-80. I have a lot of plants, all anubias species but different sizes.

About a year ago I realized the readings could be because of the plants. I had tried different kinds of vallisneria back then, like jungle and americana, for a couple of weeks. They started getting black beard algae (I think) so I ended up getting rid of all infected. Way later I sifted through the sand and found old dead roots from those plants and fertilizer tabs I didn't know were there, buried super deep, so I thought that caused the nitrates reading. But since all of that was fixed months ago, I don't know why the nitrates seem basically the same. Not lethal, but uh not good.

Would adding another anubias plant help lower it? I'm feeding as little as I can. Or do I simply have too many fish?

Thanks in advance💖

I have a 10 gallon (that is probably overstocked). I have 1 small red honey gourami, 4 different kinds of cory catfish, 2 pygmy cories, 2 nerites (my cleaning crew), 1 assassin snail that I've had for like 4 years and will never die, and 1 rabbit snail. I used to have many of them (except for the gourami) in a 20 gallon and things were perfect, but I had to downsize when I moved. I got the gourami in February of last year.

I syphon and change the water 2x a week and add new purigen or filter media once every 5-6 weeks. I scrub the sides when I see algae, I prune plants, I mean I do everything I can think of. Whenever I test the tank over the past year, everything is fine except for the stupid nitrates. They've never been the darkest red color but somewhere reddish around 40-80. I have a lot of plants, all anubias species but different sizes.

About a year ago I realized the readings could be because of the plants. I had tried different kinds of vallisneria back then, like jungle and americana, for a couple of weeks. They started getting black beard algae (I think) so I ended up getting rid of all infected. Way later I sifted through the sand and found old dead roots from those plants and fertilizer tabs I didn't know were there, buried super deep, so I thought that caused the nitrates reading. But since all of that was fixed months ago, I don't know why the nitrates seem basically the same. Not lethal, but uh not good.

Would adding another anubias plant help lower it? I'm feeding as little as I can. Or do I simply have too many fish?

Thanks in advance💖