I wouldn't recommend either of those. Take baking soda: Sodium Bicarbonate...which will only compound your problems. Vinegar is not a stable acid, so when you think you've balanced everything, a day or two later, the ph in your resevoir or bucket-o-water is out of wack again. I don't have the chemistry major to tell you precisely why just not to do it. A liter of ph-up and down is only about 10 bucks each and will last the average home grower for years.