Mayaca will grow fine without extra iron dosing.
You can always throw a handful of nails in your filter. Anything that rusts will leach iron chelate.
certain plants will redden up with extra iron...but for the most part a trace amount found in the tap is enough, and certain fertilizers will dose small amounts too.what plant needs all this iron? they make iron in dry ferts to.
The quickest is the steel wool (more surface area). Once boiled it will start to oxydize immediately. If you use nails, boil them first for the same reason as the wool. If you are unsure as to whether or not the nail has a galvinized coating, use rusty nails.