I don't have another filter & don't really want one that isn't au natural (I know things like bioballs etc. do the best job but I don't want anything that artificial).
I have thought of running the water through a bed of pumice before the cattails which would do a similar thing except I might get anaerobic instead of aerobic bacteria going in there. I know aerobes do their job faster. I guess if the pumice was higher and the water just dribbled through it would work though. Hmm . . . (My husband will be after me about all my plans again
I have one fastish waterfall & another that is just slow drip (i figure about 1500 gallons size). I might be able to put a pumice pile under the lip of the slow drip & run some water through that. Probably even pumice in the water under the fast waterfall would work. The problem is the algae covers everything so maybe it wouldn't help. With that much algae our water clarity is pretty great. I just work at removing a little bit every day. Less of that would be nice this summer.
Last year was our first year with the pond. We did pretty well for the first year really (tons of blooming lilies) 2 happy bog gardens & happily reproducing pup fish.