Just hate spending $15-20 for a small container of the HS salt when I do water changes. (about 13 months into owning HS Vanguard, will be doing 2nd water change soon.) So far so good with the cell lasting but fingers are crossed. Anyways, I see these 40lb bags for like $6-10 at Lowes and Home Depot and was wondering if it's essentially the same salt. Thanks.