I am worried about using a metal stock tank for my worms. I heard that is is ally bad for fish, so wasn't sure about worms. Just starting out and it is what I have on hand to begin with. Hoping this works out really awesome since I would like to grow worms into a promising business venture:) Thank you so much in advance for all your knowledge.
EPA says no! https://www.epa.gov/recycle/how-create-and-maintain-indoor-worm-composting-bin But it seems like they are only concerned about rust.
Yes and no , iron is no health problem regardless what the bureaucrats at EPA say; iron compounds are very common in soils. However , in the moist conditions , corrosion pinholes will develop in the steel. Also ,because "metal " likely means galvanized steel , the zinc will also corrode and it may be a problem . Plastic stock tanks are very common and not expensive, they would be a first choice. If you already have a free galvanized tank , you could line it with plastic sheet ;I recommend the rubber liner material sold to make ponds but that can be costly depending on size. If I was going to raise worms in quantity I would forget the tanks and dig a shallow hole in the ground and put in a pond liner. It would be simpler than actually making a pond. ( I have a liner pond with a bog section and earthworms seem to be pretty happy in the bog section.)