I have changed the way this website handles comments. The old system made it very difficult for me to deal with any spam comments or the occasional blank comment.
The new system doesn't currently use a captcha but does include some spam filtering. It also requires me to approve all comments before they appear, so any spam comments can be deleted more easily.
I will need to copy the old comments over to the new system which may take a while, but with any luck the transition will be fairly seamless.