I have been using 600 g disposable CO2 cylinders to provide CO2 gas to the Fireplace Aquarium and that has been pretty good. One cylinder lasts two or three months and they are a reasonably unobtrusive size. Recently though I have been going big. Welder’s Warehouse has a two extra-large cylinders combo deal. Each cylinder holds 1300 g of CO2. Surprisingly, the larger cylinders are not much taller than the 600 g cylinders I have been using so they don’t take up massively more space. The other nice feature is they come with a flat bottomed plastic collar base and stand stably upright on their own. The smaller cylinders just have the round bottom and so need to lean up against something which is always a bit of a worry.
600 g CO2 vs. 1300 g CO2
hooked up and ready to go
Larger CO2 cylinders are more cost effective
Pricewise, the larger cylinders are slightly more cost effective. With the larger cylinders you get two cylinders which is a total of 2600 g for £66 so 2.54p per gram. The 600 g cylinder costs £16.79 which works out to 2.80p per gram. Delivery charges are pretty much the same at £5 per shipment. If you were to get your smaller cylinders in multiple shipments, that would tack on additional per-shipment delivery fees. Cheaper price, less frequent bottle changes, stable base and still an unobtrusive look – what’s not to love about that?
Still not using CO2 fire extinguishers for the aquarium
The big daddy (momma?) of CO2 cylinders would be either a 2 kg or 5 kg repurposed CO2 fire extinguisher but I’m not brave enough to do that, and for the size of the Fireplace Aquarium that much gas would be serious overkill. At any rate 2 kg isn’t tremendously more than 1300 g and going up to 5 kg would need an extinguisher at least 70 cm tall which would really be pushing the boundaries on “unobtrusive looking” in the dining room…
Big CO2 tank lasts 5.5 months
The big CO2 tank with 1300 g of CO2 lasted 169 days, or about 5.5 months. I have swapped in for a new one and we’re back up and running.