i dont believe they get to 10 inches. 7 maybe,but not 106" is the most common max size, but they have been seen to grow to 10" depending on the genetics and environment they're in. Even if you go on the 6" max size assumption, it's still overstocking the tank if you go with 5 of them on top of the pictus group.
Would there be any reason not to get a second filter?
Luananeko said:All of your planned species do fine with a bit of extra current and appreciate super clean water, so a second filter would be a good idea. It's not mandatory, but definitely beneficial.
Ok and what about evaporation? My dad think too much water will evaporate, is this true?