you dont want to play with a leaky tank, trust me it will only cause headaches
go to sports replay have pat take a look at it, he’s a good guy and knows his stuff
and if your tank says 1800 psi on it, it’s prolly a CO2 tank, all HPA tanks are 3K or more
edit : reading more carefull, thats the check valve that is rated at 1800 psi, if it sees 1800 in the valve it will pop the check valve so the tank doesn’t explode