View Full Version : Tunze 6255

06/27/2017, 10:52 PM
I'm looking to possibly get this pump (2 of them) for alternating flow. My tank is way downsized for it at 65 gallons. I'm currently using dual 6100.10 that are working, but often get 'stuck', and they are 7+ years in use. I use the 6100.10 pulsing from 50% to full power, in 'wave'/alternating action (one pump pulsing, then the other). The flow is nice, and wouldnt be horrible if it was even more at the peak level. Since this pump (I THINK) has a max flow of 2500-3000 gallons an hour, and the 6255 has a min of about 1,300 then I should not have to worry about overwhelming my tank since I'm able to down adjust the flow, right? Since 1300 is << than 3000 obviously. Just seeing if i'm missing something here.

*I want this pump b/c my next tank WILL be 180 gallons plus. And I feel I might as well get these now and just use them to their full effect on the next tank. I also really like the wide flow output.


06/28/2017, 08:52 AM
I am not a huge fan of the 6255 as it is the maximum that is possible in this size pump, what I mean by that is the motor is hot and the cooling flow/surface marginally sufficient and the result is a high maintenance pump, it really needs cleaning every couple months. Even a 180 does not need 6255's. The 6155 or 6105 will suffice and the lowest maintenance and quietest would be the 6150. The 6150 is also very wide flow and 6105 includes a wide flow housing, a 6155 can be outfitted with the 6255 front housing and you would get most of the benefits without the high maintenance factor. The 6255's are really designed to fill a space between the regular stream pumps and Master Streams and are mostly suitable for 300-1000 gallon tanks, otherwise it is much better to use the lower maintenance models which run cooler and are far more trouble free. In general 2 of any of the other pumps will suffice for most needs in a 180.

06/28/2017, 09:50 AM
Hi Roger,
I really like that suggestion. Slight chance I'll get a 220 lol. I'll just get two smaller tunze's to supplement if I need even more flow. Like a 6055 or 6095.

*Can you link me to where i can get the 6255 front housing -- to go on the 6155?
**Also, I'm reading there is an issue with the pump falling off the magnet, or the "clip" holding the pump the magnet holder. What do you suggest as a workout around/fix?
**Are these pumps even more likely to last a very long time as compared to my 6100.10?

06/28/2017, 10:05 AM
I would try the 6155's as is first if you go that way, the trade off is that the flow is wider and the lack of a full cross hatch leaves some of the spin effect from the prop in the flow, the crosshatch is like a rudder and straightens the flow, the flow also has less reach with this housing.


This can happen but is not terribly common, it was worse with the 6255 but the clip was further modified early last year. If this does happen it is due to the clamp stretching out and a bath in hot water followed by squeezing it back in is all that is needed to solve it and close it back up.

The 6105 and 6155 should last about as long, 6150 should last much longer. The one exception will be the power supplies, the old toroidal coils we used could last forever, the modern switching power supplies last 4-5 years. We made that change for a couple reasons, the toroids are very heavy and added substantial shipping costs, they were also proprietary, meaning if we are closed for a holiday, hard times. The current power supply is just a laptop power supply so something close enough to get you running is universally available, they are also very light and shave a couple pounds off shipping weight and at half the price, going through 2 in the life of a pump is not a real difference over the toroid.

06/28/2017, 10:35 AM
Hi Roger,

So the longevity might be more held back by the powersupply. Can this be replaced pretty easily if/when needed? I imagine it could be if it's like the one I have for the 6100.10 since it's external to everything else.

Or is the longevity based on something else with the 6150?


06/28/2017, 10:45 AM
DC Pump longevity is mostly limited by the electronics. Until the 6150, all DC pumps have used thin film ceramic capacitors, at 7-8 years they no longer hold a charge reliably. They can last a couple years more until they no longer hold a sufficient charge. The 6150 uses tantalum ceramic capacitors with a 40 year life span. Besides this physical wear is eliminated for the most part by the magnetic levitation (no shaft or physical contact in the 6150 between the rotor and the pump), but wear mostly results in noise and spare part changes and not pump failure. The more sophisticated BEMF system gives more reliable monitoring of obstructions and jamming so the safeties stop the pump and prevent a motor burn out. Traditionally this is done by Hall sensors which tend to have blind spots and while not failure prone, can be defect prone (wrong position in manufacturing) and can shift out of position in overheats. BEMF monitors the current production of the motor instead of where the magnet is in its rotation, so it gives more data to work with and has no blind spots where a hall sensor is essentially blind to a jam between poles, BEMF would detect that no backfeed of current is being produced.

The 6150 uses the same power supply as a 6105. The power supplies are readily available and cost about $60, but in a pinch a substitute that will get you running is as close as the nearest computer/electronics store. The main variable is a typical laptop charger is 18-20V, ours is 24V so it will run a bit slower.

06/28/2017, 11:27 AM
Does the 6155 have the ceramic capacitor? if so, then the main difference in overall life compared to the 6150 would be the power supply, right?


06/28/2017, 11:37 AM
Only 6150 has the ceramic capacitor. 6155 is just a slightly stronger 6105, in all cases expect the need for new power supplies 6105 and 6150 at about 4-5 years, 6155 and 6255 has a stronger power supply, it is fairly expensive but I rarely see them fail unless they get wet, likely because it is so oversized it is not pushed ever to its limits so this power supply tends to last about twice as long. The longest possible life will be the 6150, it even has a 5 year warranty because we are convinced it is basically a forever pump but it will need spare parts such as the disc and power supply over time, but I would expect after the initial purchase total cost in 5 years will be an additional $65. 6150 is a totally different pump from the others, 6105, 6155, 6255 are essentially the same except for motor coil windings and propeller blade size and outlet size.

06/28/2017, 12:43 PM
I got it... Now the way the 6150 looks is weird lol: from:
It looks like it has 2 magnets to hold it lenghwise along the glass of the tank. So from that pic it seems like the flow is directed parallel to the glass panel it's on, and not more perpendicular, and it seems like a very long pump from base to where water flows out. (???)
Are there better pics, if this one is not representative?

06/28/2017, 03:27 PM
I found a cool video on youtube about the 6150... really neat lol:
It seems this pump specifically seems to cause actual wave action and flow. It is directed along the glass. But the set up here has them tucked out of the way, on the bottom of the back glass. This looks really nice.

06/28/2017, 03:52 PM
Yes, it has 2 magnets, the reason being that one big magnet affects the levitation of the propeller. It is also very long as we have a few magnetic fields going and a space between them is needed to accomplish the levitation. They do really fill the tank with quite a bit of flow and can be used to make a wave or directional current. In the video we were trying to show that it does both at the same time. The reason being that unlike typical pumps in wavemode we cannot pulse 0-100%, the start up to levitate the magnet prevents a wave from forming, so instead 5%-100% is used and this gives a shorter wave but paired with a directional current. Because of how the flow exits the pump, despite the bulk of the pump it can be effectively concealed in larger tanks vs more conventional pumps that have to be exposed and aimed where needed.

06/28/2017, 04:40 PM
OK.. i'm getting the 6150's :)
Thanks Roger, you were a big help as always