im new to this but it seems to be doing ok there 26 days old now and i could use some advice on if it would be ok to use a 70 watt hps to flower in this grow box its like a 3+2+5
Yea you can start now if you want to, and they'll stay small. 70 watt hps is definitely on the small side...I'm sure it would work, but it isn't even close to optimal. I'm no expert on lighting, but you probably want 250 watt at least (and if you're gonna get that, just go for 400 cause I don't think there's usually much of a price difference).
What you got is alright for now, but if you keep growing you'll want to invest in some HID lighting or maybe LED's. Also when you flower the plants usually double to triple in size. Maybe not so much with the lights you have, but be aware of the space they will take up if thats an issue.