Which wash buffer needs tuning?

Greetings fellow DBAs,

I am trying to reduce the 'Buffers Washed Dirty' for my system's default data cache  (as seen in sp_sysmon: Data Cache Management->cache: Default Data Cache->Buffer Wash Behavior section). 

I have varied the wash sizes in my 2K, 4K, and 16K pools with inconsistent results.  Is there a way to determine which pool requires a bigger wash setting?

Thanks!

Doug