Gotcha. Afaik the GH trio alone has everything the plant needs (especially in DWC bare root systems), and from what I remember when running it back in the day is that its hard to go wrong with that line unless you really crank the EC up high, which is a waste anyway.. It's always easier to fix underfeeding problems, but its also kinda hard to underfeed in DWC as long as you give them something to suck up, and keep the PH in range. If anything, a little espoms salt would probably do you better though IMO. I guess use it if you got it though, and probably around whatever amount end up adding 100 ppm total, give or take.