Rob,

I bought a Soligor 43 mm UV filter and a double sided coating circular polarizer filter for my HV20 and them works nice.

UV filter is always installed on it to protect lens and also I use a plastic cover
to protect filters from dust or scratches when I put HV20 on my Lowepro bag.
Yes, sometimes I forget to take out the cover before start recording, but I prefer don't clean so much the filters taking out coating.