Fermentation problem, AG molasses, ???

[sailor1]

I recently tried a new molasses for a rum ferment called Mother Earth Sugar Load Heavy Brix Molasses https://www.amazon.com/Mother-Earth-Sug ... B01JAMQCS2. It is designed for use somehow in hydroponics. Ingredients seem to be simple, just molasses and water. However, I had trouble getting it to ferment. i mixed a 2.5 gallon jug with 10 gallons of water, added 5 lbs of brown sugar per my usual recipe and pitched my bakers yeast and....nothing. Well, actually I tested initial specific gravity (1.200) but decided that it was probably elevated because of all of the unfermentable solids in the molasses--as an agricultural product it probably contained a lot of impurities like ash. And it checked pH and found it to be very low 3.5...but I figured the bakers yeast would still tackle it, but no luck. After a few days with no action I diluted a bit of the mash and pitched new yeast--it took off. So I diluted the main wash and pitched new yeast in proportion, but, nothing.
So...I'd appreciate any ideas on the molasses, if anyone has experience with a similar product...
And suggestions about why I couldn't get the ferment going.
My suspicion is that pH was the bigger issue, so any suggestions about how to increase it would be appreciated (calcium carbonate?)
10 gallons of unfermented wash down the toilet...I wonder what the sewage treatment plant thought of that