Feeding A Protein Skimmer

 

    When operating a recirculating protein skimmer one needs to provide a source of water approx 1-1/2 to 2 times the total system volume per hour. Many use a small feed pump to feed water to their recirc skimmer. Some tap into the return line from their return pump and others divert some water from their overflow hose connected to the stand pipe within the overflow. When tapping into the flow from the stand pipe you typically get not only water, but also a lot of air because air gets entrained with the water as it flows through the stand pipe.

    There are many ways to reduce if not eliminate this air, but it struck me one day that this idea would be much simpler. This plan is to tap into the side of the siphon overflow and siphon water from the overflow below the overflows' normal operating water level yet well above the bottom of the U tube/siphon tube. Doing this will guarantee that NO air can become entrained, the recirculating skimmer will ALWAYS be fed a consistent volume of water and eliminates the need for a feed pump.

    Well here's the basic plans. Instead of using a threaded elbow (shown in the pic) I ended up using a DIY Bulkhead Fitting. I did not want to risk cracking the acrylic while tapping the threads.
 

 

    This is what the overflow should look like in the event of a power outage or when the return pump is off:

 

    I started with a PVC adaptor, I cut 3/4" off using a miter saw which left only 3/16" of the hex. I used this modified adaptor, 1/2" barbed elbow and a rubber O-ring as my DIY Bulkhead Fitting.

PVC Adaptor Cut With
Miter Saw		 DIY Bulkhead
Fitting

 

    This is my siphon overflow which I purchased at Aquatic Eco-Systems though I modified it by installing a Durso Stand Pipe:       

Before: After:

   

 

     I removed the stand pipe

 

    

    I used a 7/8" hole saw to cut the hole for the bulkhead fitting. There are many other ways to cut this hole, but a hole saw is fool proof.

 

    The modified PVC adaptor with the rubber O-ring was installed with the rubber O-ring on the interior of the overflow.  This DIY bulkhead fitting protrudes ONLY 3/16" into the overflow compartment.

INSTALLED: BEFORE: AFTER:    

       

    Now that the overflow modifications are finished we have to be able to control the volume of water that siphons from the overflow. I chose to use a 1/2" ball valve. One can also use a gate valve or most any type of valve. The Union allows quick detachment from the protein skimmer. All that is needed is a hose leading from the barbed fitting on the overflow to the barbed fitting on the valve.

    I used 5/8” ID x 7/8” OD clear vinyl hose.

Valve and Fittings Valve Assembled   Feed Attached To Skimmer
 

 

In Operation:

Return Pump
ON		 Return Pump OF Return Pump ON
Valve Closed		 Return Pump OFF
Valve Open

    My return pump (GenX-2400) is pumping approx 225 gph up to my 38 gal display tank (total system volume = 48 gal). This modification to the overflow is consistently siphoning approx 129 gph down to the sump without sucking air! I only need anywhere between 71-95 gph to feed the skimmer so I must close the valve a bit.

 

Conclusion:

 

 


 

 

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