To cut down on my humidity in my apt I taped over the overflow, now the only air that the filter has coming in is from the little opening on the flow adjustment, will this be a problem?
No. but I don't see how that cuts down your humidity?
Doesn't your ac have a lid? I believe you would get more humidity from the openining where the filter is goign into the tank versus from the top of the filter.
Oh I don't myself see it causing problems ... My 250 is almost all sealed up... I have littel hole here and there... But they are filled with filter pad or covered with acrylic.