If you have the chance to redesign your sump, which filter will you prefer and the reason. I have use filter socks now and find is quite troublesome to wash and bleach it and wash again and sun dried it and need to change within 3 days. I don't know what the pros and cons of using filter wool ( All i think is just replace a new filter wool every week ) and I did find some related thread but all it mentioned is it might become nitrate factory. So asking reefer for their suggestion. Thanks