There have been discussions in the past about marking distance on the a nylon rode. I found something that has worked well for me. I got a can of that black liquid rubber used for electrical connections and marked the line every 50'. I put a 1/2" wide ring around the line, 1 ring equels 50', so 50' has 1 ring, 100' has 2 rings etc. I let the can sit in hot water to warm it and make it penetrate better. The rubber soaks into the line so it can't wear off. It has worked great over the summer and looks as good as the day I applied it.