1st time rum ferment question

[Spowers2]

My first time playing with molasses. In a clean bucket I added 9 Lbs. molasses, 5 gallons hot water, 4 Lbs. brown sugar, 2 cans coconut milk. Added a little nutrient and got the ph to about 5.0-5.4 (hard to tell from the molasses coloring) Then pitched some dady.

It went crazy and seems to be done 24 hours later, popped lid off bucket to check finished gravity (1.020) and it had a layer on top I've never seen before. It was like a dry, hard foam, light colored with chunks of what looked like sliced up water chestnut in it.. It covered the whole top of the mash.

I've done many mashes before and never seen anything like this, but, first time with molasses. I'm assuming it must be from the molasses.

From what I've read having nasty stuff is good for rum anyways but, just wanting some info from the pros! I've tried searching for info on this, but all I can find is info about dunder and infections. Is this an infection? By the way I used an agricultural molasses that comes in 3.5 gallon buckets, maybe something to do with it?

Thanks for any help!