"Dick" wrote in message
...
I want to experiment with CO2. I read once that Seltzer water could be
used to add CO2 to the water. If this is feasible I wonder what would
be approximate formula for a 75 gallon tank. I found quarts at my
local market with no salt.

If you plan on adding supplemental CO2 to your aquarium to enhance plant
growth, then a steady and consistent supply is needed. Carbonated water
would add additional CO2 suddenly to a tank, but it would be quickly
exhausted......within an hour or so. So really this is not a feasible
choice. For a 75 gallon tank, your choices are limited to either a full
scale CO2 cylinder and associated gear or a large scale DIY yeast
reactor or commercial unit(s). The yeast reactors work better for
smaller tanks, which you do not have.