Stuck on level 73

Answer from: Teresa
Break the black balls on level 70

Answer from: Suzanlb
@Teresa: How does that help level 73?

Answer from: Sky
The sludge stops if you pop the bubbles below it. You will likely get a few bubbles sludged but you can keep it from going all the way down. I think the key to this level is deciding how many plus bubbles you need but not necessarily going for them all. Sometimes it takes too many bubbles for it to be worth it. Look for places where you can get a pair of bubbles as well as one single one that might be nearby. Getting combos will mean you save the bubbles to get rid of the single one. Try to pop the bubbles so the the ice bubbles at the end match the color of the baby bubble. Hope this helps. You don't have to drop everything, just the baby bubbles. They are in the top right and left, so you don't have to drop the middle.