welp, the #500 is working out perfect. so happy with this setup.

i did have a slight leak happening from the bottom of the tank. but i remedied that right quick by flipping the plastic tank tube. the top end was beveled slightly differently (more uniform) and i also added another layer of protection by wrapping 1 revoultion of plumbers teflon tape around the o-ring. now its watertight as a ducks bunghole. its been over 24hrs and not a drop. nomally id have several drops in that amount of time.
but anyway the mesh that comes with it is a mystery. its 325 maybe? could be 400 but i doubt it. likely 325 or maybe lower.
my top cap o-ring is totally fine. not too tight, not too loose. but picking up one of those sets could be a really helpful move in general. i might get one just to have.
one thing to condiser on the cobra clone is the size of the nut on the neg terminal. its got a small head and the thicker gague wire like the 28 awg i have barely fits under it. im thinking of looking into bigger nuts that would fit that terminal.