PF-300 HOB Overflow

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$119.98 $119.98

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Add an overflow to any aquarium with Eshopps PF series of hang on back overflows. Adding a sump to a tank will allow you to hide equipment and while adding water volume making your tank more stable. Traditional overflows require you to drill holes in your aquarium where Eshopps PF HOB overflows use a siphon to draw water over the wall of the tank without any modifications to your aquarium. 


In most cases, we would recommend drilling your aquarium and using an internal overflow like the Eshopps Eclipse, but in some situations, a HOB style overflow may be the best option. Hang on back overflows do require more monitoring and safety precautions to be in place, but can be completely reliable if installed properly and maintained regularly. Installation only takes a couple of minutes, and the PF-300 only requires 3" of clearance outside the tank to drain water down to a sump, refugium, or wet/dry filter. Just lower the overflow box onto your aquarium and then connect your favorite type of plumbing to the included 1" bulkhead.


Model Dimensions Bulkheads U-Tubes Recommended Tank Size Max Flow Rate
PF-Nano 4" x 2.5" x 8" One 3/4" One 10-20 Gallons 200 GPH
PF-300 6" x 3" x 10"  One 1" One 35-75 Gallons 300 GPH
PF-800 8" x 3" x 10" One 1" One 75-125 Gallons 800 GPH
PF-1000 9" x 3" x 10" Two 1" Two 125-150 Gallons 1000 GPH
PF-1200 10" x 3" x 10" Two 1" Two 150-200 Gallons 1200 GPH
PF-1800 12" x 4" x 10" Two 1.5" One 200-300 Gallons 1600 GPH


What's Included?

1x Prefilter Box

1x External Filter Box

1x U-Tube

1x Bulkhead

1x Foam Cylinder

Screw(s) and Wind Nut(s)


Starting the Siphon:

can be done with a 1-foot piece of airline tubing. Start by filling the aquarium until water flows into the intake box, and then using a cup fill the external box with water until the U-tube end is covered. Remove the U-tube and place one end of the airline tubing into the U-tube. Replace the U-tube into the overflow making sure that the airline tubing is at the apex of the bend and using a pump like a Tom's Aqualifter to suck the air out of the tube until it is replaced with water. You may be required to fill either the internal or external box with more water as the siphon is created. Once all the air is removed the airline tubing must be removed or submerged. 

Once the siphon is created it is important to keep air bubbles from forming in the U-tube. If you find bubbles forming, it could be a variety of things from too little flow to microbubble build up. 

More Information
UPC 689076890144
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Product Questions

What is the dimensions of the box that goes inside the tank? Trying to determine if it will fit in the back chamber of a 29g biocube.
Question by: Dave on Oct 30, 2018, 12:00 AM
Hey Dave,
Thanks for reaching out to us. The internal overflow box measures 6"x6"x2.5". Let us know if you have any other questions.
Answer by: Jason Smith on Oct 30, 2018, 8:26 AM
What is the GPH range for this overflow?
Question by: Shae Biggs on Jan 29, 2018, 5:02 PM
Hey there,
We would recommend not exceeding 600GPH for the return pump. Take care!
Answer by: Mark Schlough on Feb 10, 2018, 2:35 PM