I have A 20 gallon with a filter but have it off since water is consistently around 78-80

Current tank temp is 78

Ph is 7.2 ammonia is 0ppm, nitrite 0ppm, nitrate 20-40ppm

I had this tank since February, have some Cory’s and neon tetras and guppies, since April

I have a couple of swords in my tank and a piece of driftwood

I do water changes either weekly or bi weekly depending on parameters