On CO2: my CO2 levels are way to low (+-1.2 ppm, PH 8, KH 5)
so i'm also going to build a DIY CO2 system. It seems easy enough.
Anyway, if you buy one of these systems, what would be the initial cost
and how much do pay to keep it going?

Regards,
Benedict


Initial cost : Co2 fermenter and tubing : under $10 , empty soda bottle :
free

additional costs : sugar, yeast, and baking soda = under $5 , enough for 3
months to a year

= very cheap