So my tank seems to be doing great ,have 12 fish so far no deaths as of yet.My question is about aqautic water from the pet shop its cheap but can't I just treat the water I need and do it myself.Any sugestions on products etc. and what would be recomended on water changes,my tank is 72 gallon .At the pet shop they recomend 5% weekly.And one more question when cleaning my gravel my filter came with a polishing filter. I understand this part but will the fish be harmed by excessive debree while cleaning gravel when the time comes, you know when the bottom gets stirred up any tips