HELP! Clones in rockwool smell moldy and musty.

Hey guys, just wanted to give a quick update. I got 100% through! There are doing great now. Letting them dry out a bit really helped as the roots did have to search for the moisture and nutes. One think I noticed was that the roots are very delicate. When I would pick up the cubes to look at the bottoms, the root tips would break off when I would put the cube back down. I ended up laying a bed of Coco Coir down so that the roots has something soft to grow into as I waited for enough growth before transplanting.

Here are some pics of my progress so far...