Boyu Dgn-520 External Filter


Mar 2, 2009
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The Boyu DNG filter range comes in 3 sizes, the 410, 460 and the 520. All have the same power specification of 4-30w and all come with a 150w heater and 4w uv with adjustable flow rates from 300l/hr to 1610l/hr. I was treated to the largest model the DGN-520 which measures 240 x 240 x 521mm, and I gave it a good workout on some of my tanks.


Test 1. Setting up. This filter was so easy to set up, 15 minutes from opening the box to it running. The amount of media supplied fits exactly in to the baskets, absolutely no need for additional media. However you can change it if you wish.







The general feel of the head clips are sturdy. The pipework is very generous for larger tanks. The stop taps are a simple turn to switch off and a push button release, unplug the lead and unclip the head for easy cleaning.



A simple push fit connector to the head for the electrics.


This filter has to be one of the easiest I have ever used to prime. Once all set up just plug in and the motor will start. Press the "S" button and everything is done in seconds! This video shows the filter filling from empty to running, the initial noise only lasts a few seconds then the filter runs almost silent only a slight hum on the highest setting, near silent on the lowest. If any air does get trapped in the filter, the "S" button can be pressed again, an end to shaking filters to release air!! The times I tested it, I never had problems with trapped air.


Upon start up the filter automatically runs at full power with the heater sets itself to 25C. A note to remember that you will need to re-set the heater setting each time the unit is unplugged if you want higher or lower than 25c. This is easily done by holding the uv button until the display starts flashing then using the arrow buttons next to the heater digital display to set the temperature. To reduce the flow, press the - button on the top of the filter, it will reduce by one setting each time. This filter is so simple to use, everything is by the touch of a button.


Test 2: Heater function. I set up my spare 240l tank with cold water and left the filter running with the heater set at 27c. This was set up in my conservatory where night time ambient temperatures would drop to around 15c. Once the tank was up to temperature it did not fluctuate at all during this test which I ran for just over a week checking randomly during colder spells. This sort of temperature would be an average household temperatures in the uk in the winter.


Test 3 Flow rates: The flow rates with the media supplied on the lowest setting were 360l/hr, on the highest setting however the rate was approximately 1400l/hr, unfortunately my flow meter was not working correctly and had to calculate the higher setting manually. Visibly you can see the difference in flow on each setting. Changing media did not affect the flow rates, swapping the bio balls for ceramic rings, adding additional ceramic rings in place of the filter floss did not affect it greatly.


Test 4: I set up the filter on my heavily stocked juwel rio 180l tank, dwarf cichlid and community fish, using my own media, sponge and ceramic rings (as it was mature), the filter performed excellent keeping the tank clear and no water quality problems. There was no difference to the flow rates with using different media. The tank temperature remained constant as set on the filter.


Test 5: Oscar tank. I set up the DGN-520 alongside one of the already mature filters in my oscar tank, using the media from the filter I removed for this test, ceramic rings, bio balls & filter floss. The filter performed well with larger debris. The strong suckers holding the intake and outlet pipework did a good job against an oscar trying to get them off. With this being a much larger tank I left the larger internal heater running so there was no need for the heater in the filter for this test.


Test 6: I returned the filter, empty of media to my 240l tank which I had left full of water in the conservatory. With natural sunlight the tank had green water. I set the filter up without any media to test the 4w uv and I was pleasantly pleased that it did clear the green water within 48 hours. For this test I had the flow setting at the midway point.


Test 7: Weather & Hillstream loach and American flagfish tank 260l: This is a difficult tank to get right with regards flow, but again the Boyu did its job with no problems and no difference in water quality. I did not use the uv facility in this test even though the tank is situated in the conservatory, because I need the algae growth for the flag fish & hillstream loach. However the flag fish are messy stripping chunks of hair algae and spitting some out making this tank a filters nightmare as hair algae chunks soon clog up sponges. For this test I removed the top blue sponge and used the media from the mature filter as the blue sponge would have become quickly clogged. This tank has a lower temperature so I did use the heater in the filter, set at 20c and there were no fluctuations in between daytime and night time temperatures in the tank.


The ultimate filter test: I finally set up the DGN-520 on my turtle tank, coping with large debris from turtles and messy food its a huge challange for any filter. Skin and bits of shell clog up filters really quickly, but the Boyu coped very well and no problems priming with the lower water level.


Over all this filter is excellent and I have thoroughly enjoyed putting it through its paces, it has coped well on different tanks, volumes of water, stocking levels etc, the heater has out performed my expectations and although I was a little reserved at only a 4w uv, it did the job clearing green water. The DGN-520 is an excellent large filter with good media capacity for larger tanks or smaller heavily stocked tanks. My only complaint would be the maximum flow rate, if this was higher along with a larger heater it would be perfect for tanks over 250l, however two on a 300l - 400L tank would filter and heat it excellently. Excellent value for money.


The Boyu range of filters are available from All Pond Solutions.



New Member
Jun 12, 2019
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Bali - Indonesia
Hi star4, does the filter still working well after 5 years? Any leak/flow/priming issue?


Jan 26, 2008
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Perth, WA
I don't think they will be responding due to it being advertising/ spam.
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