in a 6x7 room , thats 42 square feet, if u give each plant 1.5feet X 1.5 feet(2.25 feet squared) , u could put around 18 plants in that room. Which is 42 feet devided by 2.25 feet. What im saying is , 25 plants its quite a bit for that size of room, in my opinion, 18 for that room would kinda be pushing max.
But I could be wrong.
But if u think about it , if u only gave ur plants 1 foot x 1 foot, thats 2 square feet, which isnt much, and even that, would only allow for 21 plants.