Aqualoon;5132642; said:API Liquid test kits aren't always the easiest to read. It's under 20ppm because that's the color range it best fits (10ppm - 20ppm). For all I know it could be 8 or 9 but that is still under 20ppm.
My point is, that to create that kind of bioload in a tank that large with juvie fish, you're WAY overstocked, and it's only going to get worse.
I'd start thinning now if I were you, and just let your fish grow into their home.