Yes, GSH get much larger... 3" for FHM as compared to GSH which can reach 12".
An over abundance of overly large GSH can cause problems in a small pond. GSH will compete for zooplankton food sources with BG and small bass. This can cause a decrease in growth rates for preferred game fish such as the BG and LMB. In my experience, a pond with a healthy LMB population will rarely allow large numbers of GSH to reach adulthood, particularly in a small pond.
The huge number disparity is due to size differences. 2000 FHM are adult fish, 1"-3" in size... The 250,000 GSH are fry, less than a half inch in size. The fry will be heavily preyed upon, therefore you need a much larger number to ensure some survive to reproduce.
Anymore questions, feel free to ask...
