Also be aware that the most effective form of garlic is freshly pressed, not any of that off the shelf garlic additive stuff. There are two chemicals in garlic that when combined form allicin, which is not stable for more than a few hours (if I remember correctly). This means that adding those liquid garlic additives, although they smell strong, are not going to contain the anti-parasitic properties of freshly pressed garlic. This may be one reason that there is less than ample evidence of this working in the hobby. Most hobbyists are using foods 'enriched' with garlic or liquid additives, not freshly pressed.