Really the wet dry filter was an after thought. Well, after a baby bird drowned in the pool, that is. My K1 filter is made from a 20 gallon drum and handles normal bioloads very well, but when I could not the cause of a sudden spike in nitrates and ammonia, I added a homemade paddle wheel made from bicycle rims with shade cloth sails to act as a wet/dry filter. It took care of the problem until I could find the dead baby bird in one of the 4 inch pieces of PVC that I have for the fish to hide in. I am too lazy to remove it now.