to tie mono or flouro to each other you must use double surgeons knot. That is what we use building steelhead leaders for fly fishing. It will be tough to get right due to the big diameter difference in the lines but if you lube it well and get it pulled tightly it will work. Remember that it is not as strong as the modified alberto but that knot is hard to tie with mono. The double surgeons knot does test stronger than blood knots but does not look as pretty. I have built hundreds of steelhead salmon leaders using double surgeons knots using mono to flouro tippets.