Yes, the molasses that I use causes the pH to rise unlike any other time. I've altered my use of the stuff because of it, I now add it to the res, and let it churn in the res for 12 hours, then adjust pH and use it.
I'm using Sweet now, too, and I haven't noticed any difference yet. I will try Sucanat next.
The optimal pH level for hydro is the high 5's. And yes, for later in flowering, the P and K are better around pH 6.0.
HTH
