This is an excerpt from an email I received from a rep with Flying Skull ref a question I had using both Z7 and Hydroguard:
The Hydroguard was originally introduced to help make the root system bigger. Z7 was formulated to keep the roots and growing system clean. Clean roots allow you to have better quality roots and ultimately less roots. The less roots to grow the plant the better off you are in a hydro system.
What do you think of what was said about roots? Less is best when clean and strong, that is what I am getting. Seems like more would be the best if clean and strong. Still using them both. Besides, the Hydroguard has an expiration date coming on soon.