Sugar also binds nitrogen and makes it unavailable to the plant...I use sugar water when I see signs of overfert...since sugar is the simplest carbon you can really add to a plant...so unless you have caused a serious deficiency then there is nothing the sugar could have done....I use it in veg and flower...as I said, anytime I suspect the plants have too much N...and it has never caused any issue...but if you use too much sugar for the amount of water and the sugar isn't totally dissolved it can again lock out all the nutes that are there...so just flush....and if ever you decided to sugar water your plants again use 3 tablespoons in a gallon and mix thoroughly.