Hi guys, I have a couple of Vivi Novas and I hate to say they're "the older versions" because I just bought them, brand spankin' new. 
Do the newly designed Vivi Nova 2.5 heads, that sell for around $2.50 or so, screw into the older Vivi Novas? Or is the threading also redesigned so that you have to buy the whole new tank? Thanks
	
		
			
		
		
	
			
			Do the newly designed Vivi Nova 2.5 heads, that sell for around $2.50 or so, screw into the older Vivi Novas? Or is the threading also redesigned so that you have to buy the whole new tank? Thanks