You would do better to start your own thread when you have a question...just for future reference.
You want to change anywhere from 25% to 40% of your water. Syphoning is the best way to remove the water and a gravel vac attachment allows you to clean the gravel as well.
You have a couple of problems at the moment. Your tank is set up and hasn't cycled yet. This thread was designed to help hobbyists avoid this problem. Please read the nitrogen cycle article in the Articles section.
The fish you have will more than likely not survive the toxins that the cycle will produce. Further, the balas aren't really good in a 20
gal tank. They are a schooling fish...and they get quite large.
If I were you, I'd see if I could return these guys and cycle the tank first. If that's not possible, you will need test kits for
NH3,
NO2,
NO3 and
ph. Test the water every day and if the
NH3 result goes over 1.5
ppm, a
PWC will be needed to reduce that level.
Good luck.
