Danner Mag 3
By: JFettig

The Danner Supreme Mag 3 drive pump reviewed!
The Danner Supreme Mag drive pumps have been used in systems for a long time. They were never considered really good pumps, because we didn't know what really good pumps were. Back in the day, they looked for high GPH pumps. Now things have changed, We want pressure, low noise, reliability, and low heat dissipation. The Danner Mag 3 is exactly that.

The Mag 3 is a perfect ballance of that. It consumes(doesnt necessarily dissipate all that) 35watts of energy. It pushes 350GPH max and 10.5FT max. Other pumps like the Eheim have a max head height of around 6FT.

This pump is somewhat large. the pump(without barbs) measures 3.75" wide 4.5"deep, 2.5" without impeller housing. 3.25" high without output, and 4" with the output.

Take a look at this graph that Les from overclockers forums posted. It shows the flow verses pressure graphs of the Mag 3, 5, and 7 along with the curves of a few regular water cooling systems. You can see that the #3 and #5 run aproximately the same flow in the area that we would be using these pumps in. The Mag 7 is quite a bit higher, but then you have to take heat dissipation into consideration.

Note: The hosebarb does not come with the pump.

Taking a look at whats inside the box.
What came was the pump, and a prefilter(not shown). It also came with a little instruction manual with a graph(similar to above)

Shows all the innards of the pump. Note how it is sealed with an O-Ring.

The O-Ring is not an O-ring that should be used, When selecting an O-Ring, you do not want to have to streach it at all. This will cause the seal to fail. With this pump, Its kinda difficult to get a perfect seal. But it can be done, It isnt likely to stay good over time. So you should take off the o-ring, and put a bead of sealant around the outside of the housing, where the O-ring sits. I would suggest RTV silicone or Marine GOOP.

One of my favorite things about this pump is the impeller and the impeller shaft. It is extremely heavy duty. The shaft is made out of ceramic, no corosion will be going on here.

For the outlet barb, I did not want a large hosebarb going around the outside. So what I did is measured the oulet inside hole, and found it to be just under 7/16", wich is the size for a 1/4" NPT tap. the size used for 1/2" hosebarbs. So what I did is hand reamed it out with the correct sized drill bit, then tapped the outlet so a hosebarb could go inside. I would not really recomend this, it could be dangerous. The outlet could break, crack and leak. I did have problems sealing with teflon tape afterwords, so I had to GOOP it.

The inlet is tapped for 1/2NPT hosebarb, So I ordered some 1/2"NPT hosebarbs to screw in, I always order the plastic ones, the ones I order are strong, and hold the tubing in really well. Also, its kind of dangerous screwing a metal barb into this inlet. It has been reported to have cracked when cranking down on it too hard. People have fixed that by putting a hose clamp over the outlet.

ONLY USE PLASTIC BARBS, the use of metal barbs can promote cracking of the pump housing.


In conclusion, I would highly recomend this pump. It is very powerful, very quiet, low cost,and very efficient. There are a few downs to this pump, but over all, Its ranks top notch in my book.


High Pressure
High efficiency
Low cost


Impeller housing leakage

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