Rotary drum filters are not for everyone. The manufacturer/distributor will tell you that rotary drum filters are the only filters that discard the solid particles instantly, maintaining pristine water quality. It is true, ONLY if rotary drum filter works without problems. You will not know the problems until you own one. Here is our experience.

In August 2011, our then pond builder Matt Corino of Sugarloaf Koi, who was also a dealer of Koi Collection Rotary Drum Filters, sold us the largest (KC-60) model rotary drum filter for our 14,000 gallon outdoor pond. He installed it with the help his friend John Lentzis who is the US distributor for Koi Collection Rotary Drum Filters. We did not get a written warranty or even a receipt for an equipment that cost us several thousands of dollars! When they tried starting it, they discovered that it was shutting down because it was not getting enough water. It was connected to a 3/4hp Performance Pro Artesian Pro pump to pull 12,000 gallons through 4 bottom drains. But KC-60 model was supposed to be able to pull 15,000 gallons per hour. They blamed each other, then blamed our plumbing design and equipment and left.

By spring 2012, Matt Corino, a fly-by-night operator, had stopped working on the pond, collected money and had moved on, We got another plumber and finished the pond. When we tried starting the Rotary drum filter, we discovered that the filter mesh had come apart!

When we called John Lentzis, he said the mesh came apart because water was sitting in it for months. Shutting down the pond for winter is a routine in the north. A rdf manufacturer MUST design a filter to suit the climate he is selling the equipment for or tell the buyer of this problem in advance. John Lentzis lives only 60 miles from our pond. So, why didn't he tell us?

Here is why. He offered to sell a new mesh. The price of the mesh was higher than the market price. It is simple plastic mesh (like window screen) that would degrade in a year or come apart in winter. Then we had to pay him hourly charge for travel and installation. This is just within 3 months after the installation and without ever using the machine ! So, where is warranty? Nowhere it is mentioned that we had to empty the rdf in winter. So, we did nothing wrong.  He also mentioned that Matt Corino, the scammer, also told him to pack the washing nozzles and the jet pump meant for a smaller rdf so he could pay less to the distributor but charge us high. A good distributor should not agree to change parts for inferior quality. But John Lentzis did !!

Then we discovered why the rdf was not getting enough water. Koi collection claims the KC-60 can transfer 15,000 gallons per hour through it but in reality it could transfer only 7000 gallons ! So, our pump was sending out water far too faster than the rdf was able to fill its reservoir. We downgraded the pump to 1/2hp and it worked for a week. Then it stopped working. John Lentzis claimed the ballast of our GCTEK UV sterilizer was interfering with KC-60 control unit. As expected, he offered to sell a unit that works in a different frequency. Every pond that can afford an rdf will have one ot 2 UV sterilizers. The filter house itself will have some fluorescent lamps whose ballasts work in the same frequency. Why design the control unit that uses the same frequency?

We asked our electrician to resolve this issue. He said the control unit was designed and assembled by a person who had no knowledge of electricity. It is only a matter of time before either the jet pump or the drum motor burned out. he told us to buy a new, better designed control unit. We decided to buy a new rdf. After reading comments, talking to technicians from different rdf companies we came to know following.

Rotary drum filters need regular maintenance. The mesh, nozzles that spray water on the mesh, tend to get dirty. Bacteria grow on them, causing blockage. Expensive rdfs counter this by using hot water to clean the mesh. The heating is done either electrically or using an instant water heater. Some rdfs use fresh water for washing. But if fresh water is chlorinated, it must be passed through a carbon filter or dechlorinated somehow.

Good rdfs also use stainless steel or titanium mesh that do not come apart. Plastic mesh comes apart even if the rdf stops for 4-5 hours. Mesh should be cleaned with muriatic acid or bleach every 2 weeks. This routine takes 2 hours minimum. You must stop pumps, close either ends of rdf and fill the rdf with vinegar or diluted muriatic acid and leave it for 30 minutes while rotating the drum once in a while. Then vacuum the acid out of rdf and rinse it 2-3 times with fresh water before start using it. Plastic mesh disintegrates from repeated exposure to acid.

If leaves or small rocks get into the rdf inlet, they stop working. So, rdf can work only indoors ! rdf washes the mesh filter roughly every 20 minutes and uses 5 gallons of water at a time. But if there is some fault in the control unit or if the fish have spawned, or there is lot of lage in the pond, it washes continuously and throws out as much as 500 gallons a day! If you don’t have automatic refill, it shuts down when the water level goes down by just 1.5 inches. When this happens, you don’t have mechanical filtration. If you have connected the return of your rdf to biological filtration, then bacteria will be dead. There are stories about fish farmers who lost all of their fish from toxic levels of ammonia and nitrite resulted from rdf failure.

Our pond guy had convinced us to buy rdf because he said we could go on vacation without worrying about the filter getting clogged. But we discovered that if you have rdf, so many things can go wrong that you can’t ask your neighbor or your landscaper or a handyman to simply switch it back on. Is the mesh clogged? Has the control unit failed? Did leaves get into the inlet? Have fish eggs coated the mesh filter? Did the jet pump fail? Did the sensors fail?.........

This is why rdfs are not popular with homeowners. Once rdf manufacturers address these issues, may be several versions later, homeowners may try them. Until then there is always Nexus Eazypod. A simple Nexus Eazypod can work without any of these complications. You can teach a handyman, who knows nothing about fish,, to clean your Eazypod when you go on vacation.