"[Question] What makes gyms 'Rise' into tall gyms?"

#PokemonGO: Simply being curious. I'm fairly certain it's decided by the total combined CP of all the defenders in the gym, but I haven't managed to find a definitive source.I recently checked and found that a gym containing defenders with a total CP sum of 8303 was raised, while a gym with a total CP sum of 7236 was lowered. Both gyms had all 6 Defenders.I'm assuming it's something like either 7500 or 8000 combined CP.If anyone knows a definitive answer and can link the source it would be appreciated.For anyone else who is also curious, now you know that the change happens sometimes between those two values. IF it is determined by CP. If anyone have found anything else that decides if a gym is raised or lowered then please share. via /r/pokemongo http://ift.tt/2A8NDYV