Run your pump 24/7 and keep an eye on your filter pressure. Try the DE. It may just do the trick. Remember that it sometimes takes a little time for the pressure to rise so give it at least a half hour after you add it before deciding to add more. The first time I added DE to my filter, I didn't want wait long enough before adding more and then my pressure shot way up and I had to backwash it out and start over.