Hi ppl, im new to this, just started yesterday to get a small tank (W13.7" x L8" x H9") with light and filter, i started the tank with 8 guppy,6 tetra,3 bumble bee,2 cory and 2 Tropical Hornwort for plant, my question is here, is there anything else i need to add into the tank like co2 for plant(how do i do it),soil to grow other plant(where can i get the soil),how to change the water(i heard i must not change the whole tank water as this will make the fish stress), i hope my first tank of fish can survive with such environment....lol