Im in the process of setting up my first diy co2 system for my 20 gallon tank, so far im thinking of using two 2 liter soda bottles with a bubble counter which is going to be a vitamin water bottle or something similiar to that.
My only question is can you reuse the same soda bottles time after time, for the sake of not having to reseal the caps every time you need to redo your recipe.
Yes, but i would recommend you getting atleast one extra bottle because you can prepare your next mixture before the first one run out. When it run out, you have a bottle ready to go and producing CO2. Thats what iam doing right now for my 46g bowfront. Though i only use one 2 litre bottle.
for a 20 gallon, i think 2 bottles is good. So you should have 4 bottles handy, 2 bottles attached, and 2 bottles ready with the new mixture.
But yes, you can reuse the bottles, just rinse with water till its clean and remake the mixture. It takes about 30 minutes to 2 hours before it starts producing co2, which is why you should have 4 bottles handy, so when you are about to switch them off, you can make the mixture early in the 2 spare bottles =)
An easier way to refill the bottles is to always do it at night, after the tank lights are off. The plants don't need CO2 at night, so your new bottle has at least 12 hours to come up to producing good CO2 before it is needed.