i use a dyna-gro solution, which is very acidic in pure water, the silicon solution i use is very much base and i use that to raise the ph a few notches, while also strengthening the plants and making them more resistant to heat and stress. i also start my solution at about 5.7 or so, because as the water evaporates i just add regular tap water which is high in ph, and that compensates for the low ph as well. i let mine go to about 6.5 -6.7 sometimes but by that time i change the solution and everything is corrected.. as you can see in the pic the roots just go crazy in the bubbling solution. i think its the only way to go..best results so far. a guy at the hydro shop told me to use some stuff called white rhino, it was supposed to make your roots go even more crazy. he also suggested this solution that broke down the old dead roots tangled up in the rootball, i think it was called rhiostacin.
i asked the guy at the hydro shop about that too, i asked him when and why to use cal mag, he said that he only uses cal mag when he thinks that the plants are having a magnesium deficiency. the dyna-gro already has a magnesium supplement in it, along with all the other trace elements it needs too.