OK, so I've been reading lots lately on how CO2 drop checkers are the best way to figure out CO2 concentrations.

I've also read that the Dennerle CO2 Indicator is one of the better ones out there and that it comes with a reference water standard while most others do not.

How do I go about getting one of these test kits? I've only found it on-line at one place for $20. (although everyone seems to have the refill for it....) Is it really that much better than the Red Sea or Azoo test kits and worth the price?

How does the test kit work? Is it one that attaches inside the aquarium (like the Red Sea indicator) or is it external where you fill up a vial and get an individual reading...


Thanks for helping a rookie out.