Refill my Sodastream with Dry Ice- 60L How to Refill for $2.75 (ish)

Dried ice IS Co2 gas and here's how I refill my SodaStream 60L canister at home in 10 minutes. I've been re-filling from 14oz to 18oz (weight) without issues. Takes about 60-90 minutes until it's fully compressed after filling/closing the bottle. I turn the relief valve nut carefully, just a half to 3/4 turn to release remaining pressure, and tighten back up when filled. Don't over tighten it, or the main valve. Just snug, and the O ring will last. I go to Vons, a CA grocery store chain, and they have a big dry ice chest. The "Penguin" brand by AirGas is "food grade". It comes in 5-7 lb blocks. At home, I drop it to break it up, and then use a rubber mallet to granulate it. I weigh out 17oz, and by the time it's funnelled in and sealed, it's down to 15.5 oz. That's 1.5oz more than the OTC cylinder weight. Doesn't effect the cylinder. The price varies, from $2.50 to $3 per lb in 2026.. I Replace the O-ring every 3-4 refills. They get brittle and flat. Home Depot, Danco brand #96730, 10 pack, $2.50 #13 size, 7/8"od-x11/16"id x 3/32nd. I've stopped putting silicone on the threads or the O ring. Empty bottle with valve: 24.5oz without valve 19.3. add 15-16 oz of dry ice- total weight after fill- 35-36oz Using the Sodastream Diet Cola flavor mix for instance, takes about 18ml to taste good (imho) and costs 25 cents per serving. Using the Narvon brand diet cola, takes 45ml, and is not as good. Tastes like diet root beer is mixed into it. I bought in the 5 gallon restaurant size, it equals 12 cents per serving. I like the Sodastream soda flavors. But at $6. per bottle, you can buy a can of original soda at Costco for the same price. If you buy the Sodastream refill gas, it's more expensive than the actual can of soda. So, the only way to make this whole concept cost less, but taste like the brands you enjoy, is to refill with dry ice.