Need info from IT guys about web filters and covenant eyes

Hello, I really want to overcome p-addiction and my best streak so far is 9 days. I think what web filter and covenant eyes might help me a lot.
1) I work as web systems developer so it's important that any anti-p software would not mess up my browser and web settings. I once had nudity blocking software that made any html that i wrote look not right even if the code was correct. I heard that K9 is free, but is it web-developer-friendly ?
2) I have three computers at home. Does it mean that I have to buy three licenses of covenant eyes or one is enough ? And also is it web-developer-friendly ?

 

You could set up an OpenDNS account and choose the filters you want. Change the DNS in your router and you should be good.