Moisture Master filters
Moisture Master filters are probably the easiest filter to change. It comes as a disc and fits into a plastic tube that unscrews with a half turn and this allows you to remove the old filter and replace the new. You can then re attach the plastic tube half and your back in business.
Supercell has 1,2 & 3 packs of moisture master type filters in G4 media so you can be sorted with one purchase for the next 2 or 3 years and the price for three is pretty sharp.