Once my 29 gallon tank is completely cycled I will want to add two or three Black HI Fin Tetra's, joining the three White HI Fin Tetra's already present. I know that I will still need to check the water to be assured that the tank balance is correct. I plan to change 20% weekly, using a gravel vac. When do I start my maintenance regime, and is my plan ok? Thanks in advance.