sugar in the tank?! more than likely was he using unsulphured molasses? i would keep away from that in hydro unless you're doing organics with your nutes already.
what happens with molasses (this is in soil) it gets into the root zone and all the beneficial bacteria/microbes living in the soil get a good snack of carbohydrate from the molasses. in turn, the bacteria/microbes create a waste byproduct, (carbon, n-p-k other good things, depending on the microbe/bacteria) this waste byproduct is EASILY absorbed by the roots and straight up the plant. all carbohydrates do in the root system is feed the microbes, wakes them up and gets them back to work feeding your root system. the reason people say it "bulks" is because in the last few weeks of bloom most people are flushing, and that means a lot of the nutrients in the root zone are locked up, there isn't an easy means for them to absorb these nutrients. so you add molasses, and suddenly BAM!! its a buffet for the root system, and the get that last bit of what's left in the soil.
for hydro, i would avoid it. also floranectar from GH, a "sweetener" does not sweeten your buds, trust me.. I KNOW! i would say floralicious and koolbloom by Gen Hydro are worth the dollars.
floralicious gives your ladies micronutrients so i use it more as a curative, leaves start yellowing in flower i add a little in, instead of "grow" nutrient so that it doesnt shock the plant, but gives it a LITTLE of what it needs you can opt for one part Floralicious Plus or 2 part Floralicious Grow and Floralicious Bloom. if you're using it as a curative i would go for the two part, just in case you need a little grow micronutrient, and just add the bloom in with every res change, worth the money IMO.
koolbloom is worth the money, its actually a phosphorus/potash boost which during bloom the plants need more of to make bigger blooms.
koolbloom like i said above, its worth it, it actually has a chemical makeup that makes it worthy during flower. i started and finished flower with liquid, Gen Hydro recommends you start with liquid and finish with dry, something about the dry bulks better i guess... i don't know... long story short, KoolBloom and Floralicious
hope this helps and doesnt confuse you! any questions let me know.

Shack