i have an old juwel rio125 tank, the internal filter has a 204 powerhead, rated at 400lph. i know the ideal might be an external filter, but has anyone upgraded the powerhead in their internal juwel filter? i know the new 600lph and 1000lph powerheads can be attached (with the help of a new pump adaptor), but would this actually help the distribution of flow around the tank? (if anyone has a used juwel powerhead they want to flog please feel free to pm me). thanks.