Kelp meal - any powdered form, for that matter - is fine if you only want the nutrients, but the grinding and drying processes degrades the hell out of the hormones and other plant growth stimulants in them. If the product is based upon Ascophyllum nodosum, it is highly likely that the cellulose was broken down though alkaline hydrolysis, so can be high in pH as well as in the added ions such as K.
If you want the full benefits of such an addition, there's one liquid brand you should consider. I'll bet you can guess which one...