The Aquatek mini regulator is made to run directly from a paintball tank with no adapter.
I went in to the sports shop today and tried a paintball tank on it and it fit.
Hubby knows the guy at the gas filling place here in Wanganui. The gas place guy also play paintball. He said the paintball guys are selling their CO2 tanks and moving to compressed air for their markers/guns so there may be some 2nd hand CO2 tanks available. The gas place guy also said if a CO2 tank is under 1.5 litres then it doesn't require certification.
It was my understanding that the regulation was for tanks over 500ml, but I'm sure the gas place guy would know more than me. lol.
A 12oz tank or soda stream tank is about 500ml (I think - thanks google) but if I can get a bigger tank all the better. I'm hoping to get a 20oz tank, but there may be bigger paintball tanks available.
I did take a gamble importing it without checking if it fit NZ paintball tanks, but all the info I could find online seemed to suggest NZ and US paintball tanks are the same thread size...which it appears they are as the NZ paintball tank fit the US regulator.
Just waiting for a reply from gas place guy on any 2nd hand tanks, hopefully this weekend. Then to replace plug to a NZ version. Also waiting on a diffuser in the post....and a drop checker. Hopefully will be up and running soon.