You Know Those White Glass Stains

[Dude]

you get it of with vinigar but is it harmfull to fish?

and another question

do i really need co2 for a 18 gallon tank with 3 plants ?

 

[Swart Skaap]

i assume youre using the vinegar on the outside of the tank?

....and no, i dont think u need C02 for your 18 gallon tank with 3 plants.

 

[Dude]

ok thanks i didnt put any in yet