Well. I'm getting turned around here. I think flushing with distilled was the right thing to do, however, what is exactly causing those symptoms on your plant, I'm not sure if it's PH, potassium burn, heat stress or what. The fact it's on the edge of the leaves says something. Time to throw that one in the plant problems section to see what the next step is. My gut would say to stay on the course with clean water one more time, but you are probably going to want to give it veg nutes sometime prior to flower. Also your bloom nutes need some N...not much, but 0 doesn't seem right to me.
As far as the setup: I am having a hard time seeing your extractor fans. You need to make sure those temps stay down. I'm not sure I like that metal grate especially if it is heating up from the bulbs or touching them. Those 2 bulbs on the right look too close to each other. One of those break and you have glass and poison on your plants.
As far as cloning...I haven't done it, but I know there are tutorials on here, you just need to search. From what I understand, you cut at a 45 degree angle, maybe shave the stem a bit and dip in cloning gel/rooting hormone and then it takes a while...