If you are just filling a paintball tank or smaller I don't feel an external filter is necessary. Other guys here strongly disagree. That is just something you will have to decide for yourself.
I live in Florida with 90% humidity. When I fill my paintball tank with my GX Compressor I do not get moisture in the tank. (I take the valve off often to check for moisture).
I have the same opinion. I went through quite a bit of testing, filling SCBA, etc. but cannot get any conversation going regarding tests, usually just name-calling.
I have measured ambient RH (relative humidity), filled tanks and bottles, then vented the air from tanks and bottles into a test void, such as a plastic bag. The venting allows the compressed air to be measured for humidity at ambient pressure, since my humidity meters only measure at ambient (room pressure). I have found that humidity is typically <10% which is very dry according to metal storage standards.
I have found that, for gun filling, simply normal pressure release venting appears to purge the water.
I have also found no evidence of liquid water in any of my guns, bottles, or tank, nor any corrosion.
I am not claiming that extra filters/water traps are unnecessary, simply that I have not been able to detect any need for them, given the applications that I have tested. No one seems to respond with humidity measurements, so IDK how to compare results.
I do avoid adding extra volume to gun and bottle filling because it increased compressor run time, especially if not achieving improved water/humidity presence.
It would be very interesting to compare results in order to try to better understand results.