I've no personal experience with ADA ferts but I think their liquid ferts are designed around you having their substrates i.e. Power Sand, Aqua Soil etc. If you read the spec each Series Step i.e. 1 to 3 relates to the aquariums age. Step 1 for the 1st 3 months I think and so on. I know that ECA is supposed to be excellent for iron.
There's a couple of guys on here that use the ADA system so I'm sure they could help out more.