The external filter is running in my meter pool, filled with crayfish and hundreds Ramshorn snails. The animals dig and dig, the crayfish and snails eat much, the secretions are correspondingly enormous. Nevertheless, I still had to clean once the filter. The water levels are always within normal limits. Approximately after half term I put u 800/1100/2000, to make it safely across the intake screen a shrimp JBL ProwFlow sf. Now I can even cultivate shrimp in the basin. This has a favorable effect on the duration of. Only the spray bar is about cleaned once a month. The filter is whisper quiet. The only shortcoming: If you leave the pool water off completely, you have to fill the filter and pipes manually by pumping again, before letting him go again. This is at least difficult in my filter. If, however, relatively rare. Depend on recommendation. I'm going to definitely get again a filter.