V1 - top fill only, 23mm PMMA
tank
V2 - Bottom fill screw added
V3 - Orchid V2 with Kayfun nano tank
V4 - Orchid v2 with extended chimney and kayfun full size tank
I think those are the differences... I don't own one yet. I should add that V3 and V4 are clone only versions. I think
fasttech was selling so many orchids with Kayfun nano kits that whatever company makes them decided to save us the trouble of ordering separate.