co2 set up and water tests

Question
Hi!
I recently purchased Plant Care Solutions CO2 System made by Jungle.
I'm unclear about how often I am suppose to use those tablets, my tank is approx. 20 gallons and it says that I should put in tablets 2-4 times a week.  How do I measure how much CO2 is going in my tank? And what other kinds of water test will I need to do now, Alkalinity???
thanks!
renee

Answer
Hi Renee,
If you are using the Jungle Fizz tabs then it appears that you use one tab for aquariums up to 40 gallons. Probably the reason it says that you can add them 2-4 times a week could be that since it is for aquariums up to 40 gallons it might be that you would have to use more if you had a larger aquarium or if you had alot of plants or plants that required more co2 than others. It is probably going to depend also on how your plants react and if they seem to be doing well. You can buy co2 test kits if you think you need it. I am sending you some websites that might help you with the co2 issue:
http://fins.actwin.com/mirror/plant-co2.html
http://www.aquacave.com/detail.aspx?ID=1143
These explain  more about co2 and also the last website offers a co2 continuous test to help maintain the correct amount of co2.
Hope this helps,
Karen