Help- Very Soft Water

I need some help, I have a 2.5 gallon tank with some plants (but nothing else yet). I am trying to get my water quality under control...I have some good things, and some bad things...

pH, Ammonia, Copper (I plan on having shrimp) are all fine

Iron, Carbon Dioxide, KH and GH are too low...we have VERY soft water...and from what I read this will directly affect the amount of CO2...

I tested some bottled water and it also came out soft...not much help.

How do I safely fix this? I read about calcium carbonate, where do I get this and what do you recommend?

Is my nonexistant iron levels related to this?
Thanks!
Opicana

 

I'm not sure about the affects of hardness on CO2, but to increase hardness, you could add some crushed coral.

-Chelle

 

Based on the PH & KH the fish tolerance of CO2 can be determined.
Note that KH is buffering capacity of water, And higher the KH more CO2 will be in the safer zone or the tolerance zone for the fish.

Refer to Chuck gadd's site for measuring the safe levels of CO2 for a perticular PH and KH.

As far as KH is concerned yes one can increase the KH by adding Caco3, refer to the Chuck gadd's site for adding Caco3, But i feel your tank is too small to increase PH or KH & hence its my word of caution, I would be extra careful in altering the parameters.

Caco3 is commenly available in India, Not sure about US... Others might be able to help you.