I made my own moisture trap out of a clear plastic bottle, of about a litre, filled with dessicant beads. Thin sheet of filter foam above and below the beads, holes drilled around the base for air to enter, tube out of the top to the pump inlet.
I used the type of beads that change colour as it absorbs the moisture so you know when they need drying.
The comercially available traps all seemed to small to me.