Rotary Drum Filters for Aquaculture & Koi Ponds

Flow from turnover: Q = water volume ÷ turnover time. Comparison flow: Q × (1 + your allowance ÷ 100). If inlet TSS is entered, the suspended-solids mass passing to the filter is Q × TSS ÷ 1,000 kg/hour. This is circulating inlet mass, not captured waste or daily solids production.

The first catalogue model at or above the comparison flow is shown for discussion. Changing mesh does not apply an assumed capacity multiplier. UV treatment performance is not assessed.

Research shows that screen selection depends on particle characteristics and operating conditions: Dolan et al., 2013; Gregersen et al., 2025; Tawfik et al., 2023. These studies inform the method; they do not certify Pureflow model capacities.

It strains fish waste and uneaten feed out of the water through a fine stainless steel screen, then washes that dirt off the screen and sends it to drain automatically. Because solids leave the system within minutes, they don't sit in a filter rotting away and releasing ammonia, nitrate and phosphate back into the water.

For most koi ponds and every fish farm we work with, yes. A sieve or bead filter traps the same dirt but someone has to clean it, and until they do the waste keeps breaking down inside. A drum filter cleans itself whenever its screen gets loaded, so water stays clearer, the biofilter has less work to do and you spend far less time on maintenance.

Our Standard and Pro drum filters use a 75-micron screen in SS 316 stainless steel. That is fine enough to give koi-show clarity and to protect a RAS biofilter, without washing so often that you waste a lot of water. Finer screens catch a little more but wash more often; coarser screens wash less but let more fine dirt through.

Size it by the flow you will actually push through it, not by pond volume. Work out your pump or gravity flow in m³/h, then pick a model whose rated flow sits comfortably above it. If you feed heavily, as on a fish farm, go one size up, because more solids means the screen loads faster.

They share the same body sizes, flows and connections. The Pro version adds UV lamps built into the unit, which saves you buying and plumbing a separate UV steriliser. If you already have UV, or want to size it separately, the Standard model is the simpler choice.

Gravity-fed is better if you are building a new pond with a bottom drain: water flows into the filter by itself, waste arrives whole and the pump only handles clean water. Pump-fed suits existing ponds without a bottom drain, because the filter can sit above water level, although the pump chops up some waste before it reaches the screen.

Usually it is one of four things: clogged spray nozzles, a dirty or badly set level sensor, more flow than the model is rated for, or simply too much feed going in. Clean the nozzles and sensor first. If it still washes constantly, check your flow and feeding, as the filter may be undersized for the load.

Very little. Check the spray nozzles every few weeks and clear any blockage, keep the level sensor clean, and look over the screen for damage. Make sure the waste line runs freely to drain. Stainless screens last for years, but replace one straight away if it tears, because dirt will bypass it.