Sodium bicarbonate vs sodium carbonate

[Duckhams]

Sodium Carbonate (Soda Ash) will significantly raise your PH for a short time after its's added and is more commonly used to 'maintain' alk/PH levels than Bicarbonate. Sodium Bicarbonate doesn't have such an impact on PH and is better for larger adjustments to your alk, which can be handy when setting up a new tank, QT etc. I'd go with the Soda Ash for daily dosing personally, however you may find the Bicarbonate goes a little further as it takes less to mix a gallon of solution. http://www.bigreefdepot.com/Bulk-Additives-s/149.htm