If I were using a bubbler; I would definitely invest in No-Wilt, or Miracle Grow Leaf shine. You spray this on your clones as soon as you place them in a rooting cube or system Thiese products provide the cutting with a waxy type liqyud, and allows the plant to stand up and thrive without the use of a humidity dome.
2 big points when taking clones. 1… PLace them immediately in a vessel of water. This will keep you from getting an air embolism as mentioned above. 2… Before placing in medium or system; Dip the ends in a rooting powder,
Leaf shine and rooting powder is available at any garden center. 