I unexpectedly ran out of Sodium Carbonate and want to use Arm and Hammer washing soda. For paper developers I just assume that it's crystal and convert 100 grams crystal = 43 grams monohydrate and then I adjust the carbonate like crazy anyways. Now I need it for film and want to keep the activity at what I'm used to. Do I need to make a saturated solution and start from there to know precisely how much carbonate I have and if so how many grams per liter are in a saturate solution of sodium carbonate? Or can I just use the conversion because it will be close enough? I hope one of you chemistry types can help.