Thank's for the info. I'm mostly just doing 1 cap of seachem iron/comp once a week sometimes skipping a week. This is a low-tech 40 breeder with mostly root feeding plants. I keep cutting the rotala all the way down to gravel but seems to always come back.
Very nice looking low tech tank! If you're satisfied with your dirt and it's giving you results then there's no reason to stress. If you decide your plants are not getting everything they need because your soil may be weathered - go ahead and place some root tabs in there and forget about it.