I agree - I only use standard "Miracle Grow" for vegging and a little generic tomato feed for flowering. I also use ordinary (albeit good quality) potting soil (NOT compost!) to grow in.
I regularly pull the magic # from a 600W HPS when I grow a good strain like Satori.
A lot of the "specialised" cannaibis ferts are little more than snake oil* IMHO. Even if they are better than the standard ferts from the local superstore, the extra benefits will only be realised when the growing conditions have been really dialled in for that strain.
I'm all for organic cannabis specific nutes as I think when combined with a good soil medium they provide a larger margin of error (no salt build-up, no need for PH adjustments, harder to overdo it, ect). The issue that I have is with all the "extra stuff" these companies would have you buy.
Example: BioBizz makes
(i) BioGrow and BioBloom - standard N-P-K formula fertilizers which I use (at a cost of less than $30 per year) and like
(ii) Plant strengthener - Leaf Coat (wtf?)
(iii) Plant energy booster - BioHeaven
(iv) Bio-stimulants (Root Juice, Alg-a-mic, TopMax)
They would have you believe that your yield and quality is going to suffer if you don't use (ii)-(iv). I've used Root Juice, TopMax, and Alg-a-mic, and don't believe they contribute to yield or quality in my growing environment. Most other companies have a similar range of plant tonics to "compliment" their N-P-K fertilizers.
Look around the boards here - there are many beginners literally kiling their babies by throwing to many nutes too early at them. - Much better to get the growing technique down before playing with so called "miracle" products that can cost 10 times more than something very similar.
Well this is a different topic, but it is probably as much the fault of the manufacturers who write the instructions on the bottles as it is the fault of the growers.
The sticky in the Madala forum entitled "Fertilizing Wisely" is worth a read - http://www.icmag.com/ic/showthread.php?t=13689
Pine