I went back and read the recipe again. So, the bicarb is being used for the salt replenishment and the salt substitue has an ingredient in it that provides potassium?
So, second question. Baking soda doesn't dissolve like salt does, do you find it laying in the bottom of the waterers?
I have to ask, why the salt substitute? The goal is to replace the sodium the birds have lost so I don't understand that. Is there something I don't know about salt substitutes?
The bananas & strawberries will supply some of the potassium the birds lose when its so very hot. I don't have jello around so I can't say whether there is any sodium in it, the fruit is supplying some though too.