I've got a couple experimental walstad-style tanks (actually buckets) growing some extra plants. They seem to be doing well, except that the dwarf sagittaria all have yellowed leaves. I'm guessing iron deficiency, which I've heard sags are prone to. So, I need a way to add iron to the soil in a way that will not totally disturb the substrate. I'm thinking of either a) injecting liquid iron supplement into the substrate using a dropper or b) freezing liquid iron supplement into small cubes and then shoving them into the substrate with tweezers. What are your thoughts on either of these methods? Is there some other way that would be easier/more effective? I've never used a soil/sand substrate before, so not sure how best to remedy this without tearing up the substrate
The tabs aren't too big, they're very similar in size to a medicine tablet and made from the same material so they dissolve in water. With clay, you don't want too much in one area. 1 tab every 3-4" should be enough.