mud in pool

[Frustrated with mud]

We purchased a new leisure pool fiberglass pool. It was almost completed when a huge amount of rain washed mud into the pool. Now the pool is filled with fine particulate mud. We have a cartridge filter, and we have been washing and washing it, however it is making very little difference. Does anyone have any suggestions as to how to expeditite this process? At this rate, we will be lucky to be swimming in the spring!