well, to be straight up with you...and i know this may be something that causes some to shout me down, but if you read the ingredients, you will see there is not a need to buy both. that was really just a fox farm marketing ploy, man...
the only difference is that a 'few' of the ingredients have slightly different mixture ratios, but it does not make a difference at all and i even know hydro store owners who refuse to even carry kangaroots because of it...they say they feel it is a less than noble sham....loosely translated.
but i use micro brew often...it does not hurt to use it often....perhaps wastes it though....fox farm has a website that gives ratios and times...