Internal circulation in my 400 l tank

Figure 1:


I used three powerheads Maxi Jet 1000 for internal circulation in my previous circulation setup for 400 l reef aquarium , but after reading some articles about the Tunze pumps, they sound a whole lot better, so I decided to replace Maxi Jet 1000 pumps with Tunze electronic or Tunze Stream pumps.

In my current circulation setup water movement in the aquarium is achieved with one Tunze Steam pump (18 V transformer, 11000 l/h) mounted on Belimo LM24 device, which is used for rotating Tunze Steam pump. Installation of Tunze Stream on LM24 is represented on Figure 1. Additionally I installed one Maxi Jet 1000 for circulation behind rocks, but contribution of this pump to total circulation in the aquarium is very little. Eheim pump 1250 is used for external circulation between pump and sump and contribute with 800 l/h to internal circulation. Total water movement in the aquarium in new setup is 12800 liters per hour.

I am very satisfied with my new circulation system, so I decided to write a short article with more detailed description. Thanks to dr. Darko Friš, who introduce me Tunze electronic pumps and Dejan Škrinjar, who found excellent Belimo LM24 product.

Turbelle® Stream 6000, 6100 pumps are controlled electronically, so I use this feature to simulate the various current conditions in the sea. At first I was planning to use 2 X Tunze 6100 with  a multi-controller, but after that I found out that system consists of one Tunze Stream and Belimo LM24 is better solution. I bought Tunze Multi-controller, so I use this controller, thought Single-controller has all functions required for my setup.

The following simulation functions are used in my aquarium:

1.) Wave simulation
The maximum and minimum output as well as the pulse time of the pumps can be set easily in Multi-controller 7094, so I use Multi-controller with pulse time 5 seconds, minimum output 30% and maximum output 100% for wave simulation.

2.)No waves  during  night
The output of the pumps is reduced during the night to Minimum output continuously  (30%) . The photo-electric cell  is supplied along with Multi-controller 7094, so I also use Multi-controller  for this function.

3.)Tide simulation
Multi-controller 7094 supports this function, but pumps are switched on or off alternately.
According to my opinion Tide mode is not the best solution with multi-controller and Tunze Stream pumps. If you program multi-controller to Tide mode, pump will be switched off and there is a problem. When pump is switched of, it is possible that small fish will enter in pump and will be damaged when pump will be switch on again.
 But on the other hand Tide mode (6 hours) together with pulse mode (waves) is the most natural combination, so that is the most important reason, why I searched  for another solution. Figure 2: Tide simulation

As it is described in next chapter  I found out that only one Tunze Stream generate circular stream in my aquarium. If a pump is placed in rear corner of the  aquarium as presented on figure 2 and output is directed diagonally towards  the front side (40 degrees, magenta color) ,current in my aquarium is clockwise oriented , but if  the output is directed parallel  with the rear aquarium plate or little diagonally towards  the rear side (-20 degrees, blue color ), current is anti clockwise oriented . This is the basic idea how to simulate Tide.

I use Belimo LM24 device for rotating Tunze Steam pump and control this device with my home made Aquarium Controller.

The new system consists of the following pumps:





Declared pump output

Actual pump output

Tide simulation

Wave simulation


Eheim 1250

in sump 1,1 m bellow aquarium


1200 l/h

800 l/h




TunzeStream (18V transformer)

in tank


11000 l/h

11000 l/h

Rotating Tunze pump with Belimo LM24

Pulses every 5 sekunds  30% do 100%



in tank


1000 l/h

1000 l/h



Figure 3:Tunze Steam and transformer

At first I was planning to use 2 X Tunze 6100 with  a multi-controller, but after that I found out that Tunze 6100 and Tunze 6000 are nearly identical pumps. Actually pump and driver are equal, only transformer is other model. So I decided to buy pump Tunze 6000 and multi-controller and test this pump with different transformers in my reef aquarium.
Pump Tunze 6000 uses transformer 2X12V 20VA (Europe) and pump Tunze 6100 uses 2X 20V 60VA (Europe) transformer. Tunze also supply transformer 2X16 V used for pump 7300/2, but I found out that 16V transformer also works with Tunze 6000 and actually change Tunze 6000 in more powerful stream than Tunze 6000 and less powerful than Tunze 6100.

I mounted pump Tunze 6000 in my aquarium and then made test  with 12V,16V,18V and 20V transformer.
According to my test, 18 V transformer produces the most appropriate stream for my aquarium. One Tunze 6000 (18V ) is enough for my 130 gallon tank, because this pump generate circular stream in my aquarium

Installation of my system, which consists of :Driver, Multicontroller and Transformer (18V, 120VA),  is ilustrated on Figure 3.



Figure 4: Installation of LM24 on Tunze mounting accessoriesBelimo LM24

Belimo LM 24 is the smallest model of Direct coupled non-spring return actuators, 35 in-lb minimum torque (4 Nm).

The actuator is not provided with and does not require any limit switches, but is electronically protected against overload. The angle of rotation is mechanically limited to 95°. When reaching the damper or actuator end position, the actuator automatically stops.

I mounted actuator directly to the piece of  plastic pipe (16 mm) with a universal V-bolt, which is also part od Belimo LM 24. Other end of plastic pipe is connected to Tunze mounting accessories, supplied together with Tunze Pump as you can see on the Figure 4.  

Figre 5:Actuators may be powered by 220 VAC or 24 VAC/DC depends on model. I use model prepared for 24 VAC/DC. The same voltage level is used for power supply and control. The simplest solution consists of the LM24 for 220VAC power supply and simple Timer, which cost less than 15 EURO.

I use two relay outputs of my home made aquarium controller  for controlling LM24. LM24 has very useful feature. It rotates very slow,  only 1 degree every second. If  I need rotation for 20 degrees clockwise, I close relay contact for clockwise rotation and vice versa, so if I need rotation for 20 degrees anti clockwise, I close other relay contact for anti clockwise rotation.

There is one part of  program for TIDE Simulation in Basic.

if (((HOUR MOD 12) = 7 ) AND (MINUTE = 0 ) AND (SECOND < 20 )) then goto WAVE_F    ' 55
if (((HOUR MOD 12) = 7 ) AND (MINUTE = 10) AND (SECOND < 20 )) then goto WAVE_R   ' 35
if (((HOUR MOD 12) = 7 ) AND (MINUTE = 20) AND (SECOND < 60 )) then goto WAVE_R   '-20
if (((HOUR MOD 12) = 7 ) AND (MINUTE = 30) AND (SECOND < 50 )) then goto WAVE_F   ' 30

if (((HOUR MOD 12) = 1 ) AND (MINUTE = 0 ) AND (SECOND < 60 )) then goto WAVE_R   '-20
if (((HOUR MOD 12) = 1 ) AND (MINUTE = 10) AND (SECOND < 50 )) then goto WAVE_F   '-30
if (((HOUR MOD 12) = 1 ) AND (MINUTE = 20) AND (SECOND < 60 )) then goto WAVE_F  ' 55
if (((HOUR MOD 12) = 1 ) AND (MINUTE = 30) AND (SECOND < 10 )) then goto WAVE_R  ' 45

WAVE_F  anti clockwise rotation

WAVE_R  clockwise rotation