Dishwasher Powder

Ok I have had an though (shocking I know), I have converted from using rinse aid in my dishwasher to just using vinegar & this is working fine, but now that my dishwashing powder is getting low I am wondering why I am still even looking at buying it. Surely I can make it.

Dishwasher Powder
1 cup bi-carbonate soda
1/4 cup salt
1/4 cup citric acid

Mix thoroughly and store in an airtight container. Use 1 tablespoon at a time.

Seems simple and I have all of these ingredients here, I might just make half the amount so I can make sure it works. I will reuse the container that I bought my last lot of dishwashing powder in, just as I reused the old rinse aid bottle (trying to pour vinegar into a small hole from a 2 litre bottle doesn’t work so well.