what is a diy 2 part system
try searching for Dr. Randy Holmes-Farley improved diy 2 part system.
It is basically a diy calcium, carbonate (alk), and magnesium system. And uses calcium chloride, baking soda, Epsom salts and magnesium chloride. Calcium chloride is available from concrete redimix companies for like ~25 for a 50 pound bag. It is used to speed hardening of concrete at lower temperatures in winter. It and magnesium chloride are also used as paving/sidewalk Ice melters also. Magnesium chloride is harder to find but I found a local industrial supplier. it was more expensive at ~$30 for a 50 pound bag.
There are also companies as mentioned that sell lessor quanties at lessor prices.
The 50 pound bags will last literally for decades on any normal sized aquarium. I used to give it away at local frag swaps so perhaps some locals around you may have some.
At any rate I suggest you review the on-line articles. It is a very good explanation of how and why to dose calcium, carbonate, and magnesium
my .02