I bought some liquid CO2 from PetSmart, is this ok to use in planted tank if I can't use a CO2 tank set up?
Yes, using these kinds of products will be fine in the interim. Pressurized CO2 is better, however.
As chevyguy8893 mentioned, some invertebrates and plants are sensitive to these products (Seachem's Excel, API's similar product, Metricide, etc etc).
That is really odd; I thought CO2 has no liquid state at pressures below about 5 atm!
Hahaha, funny guy