humic acid is beneficial in hydroponic systems. However it's usually a liquid and doesn't have additives like kelp. What's your reasoning for wanting to use it? If your using a balanced
nutrient solution you shouldn't need additives, and while humic acid is beneficial to plants, it's most beneficial and most often used with organic
nutrients and/or compost teas. If your just adding stuff because a salesman says it's great to add, your probably wasting your money.
P.S.
Nothing will clog pours of the plants root system unless it's not manufactured correctly, or you don't fallow directions. Unless it's manufactured or over used in a way that causes a sticky residue, it's not going to clog the roots. That doesn't mean you should add or use anything you want. Because everything you add will affect the pH and/or nutrient balance. If your going to add something you should know why your adding it. as well as how it will affect your nutrient solution.