Agree w/Gary.No the soda will only dissolve to saturation (the ideal mix) any extra will just sit in the bottom of the bucket.
Vic, when I was experimenting with nickel plating, I hooked an ammeter inline with the power supply so could monitor current.... then I added salt (would be soda in your case) until the ammeter showed the amount of current I was shooting for.
So, hook your meter inline with it on the 10A scale and see whatcha got for current draw.