Changing nutes.

Ok So this is my first grow, right now I have 4 clones which are about 3-4 inches tall under a 400 watt MH bulb. There are in rockwool and I'm feeding them a combination of superthrive and floranova i believe. (i didn't mix it) I'm having some browing on the leaves and someone advised me I had a calcium deficiency and to get cal-mag. So now I have calmag, superthrive, and floranova and i'm not sure where to go from here. I told someone else I was going to use cal-mag and they said it was too soon. So right now I have 2 completely different opinions and I wanna see what some other people think. I'm pretty much just looking for a solid nute system and I'm nervous I'm gonna mix them wrong or give it something too soon and end up killing my plants.

I've been misting the leaves with the superthrive/floranova combo too, someone mentioned this could be a factor in my leaves turning brown from the acidity in the mix. they said I should be misting it with regular tap water. i wasn't sure if I should or not because of the ph in the tap water. i wasn't sure if it was a good idea or not. any thoughts on this?