You never need to add root tabs. Plants grow fine with just the water being fertilized. They grow better with both the water and the substrate being fertilized. Laterite is not a fertilizer. It contains some iron, which is helpful to the plants, and it was very helpful back in the dark ages when people didn't fertilize the water at all, and their plants needed the iron. But, you still need to provide N,P,&K, plus trace elements to grow the plants at any rate except very slowly.
Thanks Laura. I have pressurized co2 and using EI dosing method. I have stem plants and some swordplants. My plants are doing ok..I have a few root tabs on hand that was why I asked. If it doesn't hurt, then I'll use them. :icon_lol: