I have tried most of the big brand nutrients over the years and decided to give Vitalink Hydromax base feed a go for my last grow. I could not be happier and to date Vitalink seems to out perform anything else I have used used in every way. For this grow I have used their full line up (it all seems to make sense and has been well tested) so far my plants are looking better than any grow I have ever had.
The res is very stable, I test every day and couldn't be more pleased, slight EC drop and a little PH rise just as it should be. I have a top up tank of plain tap water on a ball cock feeding the main res and add more feed to the res when necessary.
Don't know why I have never used Vitalink before but pleased I did. Their Fulvic Acid makes plants ravenous. Their feed chart also makes sense although I do feed at the very low end of the EC/PPM they recommend and at a slightly higher PH.
As soon as I use up my GH 3 part I will be switching to Vitalink veg feed.