Very cool that you started a journal! Sorry I missed it until now. But, caught up and will give whatever help I can as a dirt guy vs hydro. Your girl looks great though and I agree with Joe, don't overreact on the burnt tip. Make small adjustments so you don't end up chasing your tail. Remember that this is a very interconnected hobby and it all plays together (humidity, temp, nutes, water temp etc) so your burnt ends don't always mean the same thing mine do. IE: Read lots before you make a decision.
Aquarium water from doing fish water changes is a great fert for sure. I have used it mostly with large outdoor gardens though that would take all I could give them and never blink. I have access to lots but don't use it on my indoor garden because I have no way to quantify how much I am applying. I would like to though and need to figure out how to integrate it into my garden. I agree with Joe again here though and I wouldn't put fish water near your hydro unless you were go all into aquaculture and knew all the complexities of that.
Looks great and welcome to the greatest virtual place on earth