co2: all depends on what your using to diffuse, but very easy to get down, I've had co2 off for a day, another day would've had some melt age of the plants, co2 is very important for this plan but doesn't need to be cranked or blasted
EI: ask barr
In two cases i have known, the two people started using GH booster and their syngonanthus went down hill
Barr may say otherwise about the booster
but me personally i would ditch it and the CAno3, calcium is not good for this plant. Or hardness or something along the lines.
Me myself i use pure RO
If i weeren't gonna ditch the boosters and such, just dose enough for the degree of just 1 or below. But I am sure, this is your problem here, especially at 7bps (how do you even count that)?