DIY: Make your own Soda Ash cheaply
You can buy baking soda anywhere. Supermarkets, Walmart, even the Dollar Store. A box costs $0.99 and is perfectly safe for your reef. Baking Soda is sodium bicarbonate which can be used for baking, cleaning, and deodorizing. And we hobbyists use it to buffer the alkalinity level of our aquariums, too.