Well I have some good news for you. my bog is 20x8 and 6 feet deep with aquablocks i am only pushing in the neighborhood of about 6000 gph . I HAVE ONE PUMP, it pushes 12,000 gph that splits off three ways.
1. there is a 2" pipe that branches off the main three inch pipe where it pushes about 3000 gph to two return circulation jets in the main pond.
2. The three inch line then runs up to the bogs where another 2 inch line taps off and feeds a peastone bog with about 3,000 gph.
The 3 inch line then feeds the main bog with about 5000 gph yes the math is short assuming loss of flow due to head pressure.
So the problem is not the holes in the bog but more so too much flow to the bog. The whole idea to a bog is to give the bacteria in the bog a chance to pull nutrients from the water. A bog your size I'm guessing is 4'x4' And i would lean toward 1500 to 2000 gph . So build a second bog , maybe a bio falls or return jets for circulation could be your solution