5 plants in 80x80x180cm tent?

It doesn't really matter, I would say 3, then you can also do LST well. Otherwise, 5. I think, but that will be the jungle. Unless you have small strains. Small varieties.

I was too thinking about growing 3 but then i thought it could be a waste of space. i'm already growing 3 autos on the other tent and maybe i'm getting greedy lol

Hey bro! 👋😇 I would recommend growing one big plant in a 20-30 liter pot in that space! It would be more cost-effective and easier to keep an eye on one strain, one pot... than on different strains... with several pots... But you can give it a shot - grow 4-5 plants in that area. Good luck, buddy! 😇✊

I think it would be difficult, my friend. As soon as they starts grow bigger they will need some space on the sides as well. I have a tent slightly bigger then yours and growing three plants there I do not feel like I can place an additional one there easily. Do not forget that you will also need space for maintenance. I would recommend to start with three plants to not overload it..

Can only try it to see if it works. Theroy is more plants = more buds. Sometimes better to keep bit of room for light to penetrate bottom but nothing wrong with using your space

I got good ventilation and extractor with a decent humidifier.