Used many cloning pods to max out population and this is the best i could get.

I did use a serum on this planet and population was increased to 17k and used a pod and the overall population was brought up to 13k. Any ideas why this is?
these are all the effects currently on the planet:
Enslaved Prisoners : Buildcost -50%
Ion Repulsor : Defense +30%
Longevity Serum : Population +50%
Lazuli Darkmines Effect : Attack +25%
Xecti Signal Repeater Effect : Research +10%
Barrier Nexus Effect : Defense +20%
Barrier Nexus Effect : Defense +20%
Galactic Concord Station Effect : Defense +10%
Lazuli Darkmines Effect : Attack +25%
Astrobiology Ward Effect : Population +50%
Bioship Landing Platform Effect : Cloak +225
Lepus Chromatic Gateway Effect : Population +30%
Sarkonis Headquarters Effect : Defense +10%