There is potentially a much simpler (free) solution to your problem ..

https://www.opendns.com/home-internet-security/

Setup a consumer account, configure the Family Shield, set the ClearOS DNS service to point to the OpenDNS servers, and the content blocking is all taken care of for you.
Of course, using this option will also stop you accessing adult material unless you bypass the setup by connecting to the WiFi on the WAN side of the COS box (and thereby bypassing the OpenDNS lookups specified by the COS box).

Be aware though, that you also run the risk of double NAT - no idea how old your kids are, but if they are playing online games (eg XBox/Playstation), you might run into problems.