Lagniappe

Tha'll do, Chris. that'll do (I've been watching Shrek).
I think tomatoes are a great choice for this because they're as demanding or more so than bananas and while the symptoms may show up a little different, it gives a grower some perspective as to what's going on...er....plant-wise.
Great job!
This is why it's so important to change nutes on a regular basis too. Some of these may be depleted faster than others and there's no way to know exactly what's being used up without chancing a deficiency.