Tank DIY: Technical Details

Tank DIY: Technical Details

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Tank DIY: Technical Details
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There comes a point in a hobbyist's life that s/he wants to own a tank tailor made to the needs of its inhabitants. Such a tank should also take into account other parameters, such as ease of maintenance, for example. I have myself designed and constructed some of these tanks with the help of my good friend Andreas Iliopoulos. Below you will find a presentation of the technical aspects of two of my tanks, the 1300 lit non-mbuna tank and the 500 lit mbuna tank. It may be that your needs are different to mine but I hope that discussing the things I took into account will help others too. 

1300 lit Non-Mbuna Tank


Filter Compartment Diagram 

As opposed to the traditional sumps the filter compartment is constructed within the main tank boundaries. It occupies one end of it and in the case of my tank it has a total capacity of 138 lit. (10% of the total volume of water). It is constructed of 8 mm glass and has four compartments (see photo and diagram). The first contains the heaters. Water passes through sponges located behind the inlets so the big size debris is collected there (see 3-D view diagram for the route of water in the filter compartment). A plastic inlet with narrow opening connects the first compartment to the second. The second compartment contains filter moss (Hagen filter material) and a column of activated carbon (in a nylon stocking). The second compartment is connected to the third one in the same way. All plastic inlets are located as further apart from each other as possible (see photo), so the water is forced to travel through the whole body of the media. The third compartment contains the biospheres with the nitrifying bacteria and it is the largest compartment of all. A drainage hole with a valve is drilled at its bottom allowing quick removal of water during massive water changes (400 lit. every other week). The fourth compartment contains the two water pumps (a total capacity of 4.600 lit. per hour). The front glass of the fourth compartment has two drilled holes through which the clear water is returned to the main tank.

The water loses much of its flow speed as it travels the 2,55 meters to reach the opposite end of the tank. There is practically no surface water movement at a distance of 2 meters from the pump outlets. In order to help the water return to the inlets of the filter compartment and increase water movement, six internal sponge filters are located at the opposite tank side (total capacity 5.400 lit. / hour). An elementary mechanical, chemical and biological filtration is performed there, too. The six internal filters have built in compartments for activated carbon. The  advantage of this construction is 1) the in situ water changes which are performed in the compartment itself 2) the ability to remove as much as 600 lit. from the tank when a general medication is required (which results in great savings) and 3) the ease of changing filter material without stopping or carrying anything.

Left: photo of the filter chamber from above. The four compartments and the layout of the plastic inlets is shown. The blue biospheres are still partly above the water level. The photo was taken while filling the tank for the first time (Dec. 98). Right: filter diagram: 1) sponges & heaters 2) filter floss 3) biospheres 4) water pump. 

Water Flow

Ensuring a proper water flow is of paramount importance for the well being of the fish. Below you will find a diagram of the water flow of my non-mbuna Malawi tank:


Legend: [1] Detail of the connection of the water hose [1] on the bottom of the tank. The hole was drilled on the glass before tank assembly. The valve was added while building it, in the third compartment of the filter, [2] This hose will empty the tank in less than 30 minutes, [3] The 3500 l/h water pump, housed in the fourth and last filter compartment. Again, a hole was drilled on the glass separating the filter from the main tank before tank assembly, [4] The 2500 l/h water pump. The outlet of the pump is glued on the side glass and the water is forced to travel in parallel to the water surface, [5] One more 3500 l/h water pump which only works in summer for extra agitation on the water surface and a better gas exchange,[6]and[7] Self-cut sponges are used as pre-filters for the intakes of the two water pumps.



The wiring of the 1300 lit tank is as follows:


Legend: [1-8] Electric outlets. Each one has 5 grounded positions for appliances and an on/off switch. Outlets [1-4] are powered by wall socket [16], while outlets [5-8] are powered by wall socket [17] to spread the loads. Outlets [5-8] are powered by UPS [9] which can support the system for an additional 2 hours. Outlet [1] powers the 3500 l/h water pump [20]. Outlet [2] powers the three heaters [19] or the fans [18] in the summer. Outlets [3] and [4] are used to plug other electric equipment or tools (drills, electric screwdrivers etc). Outlet [5] powers the 2500 l/h water pump [15] and the three timers [11], [12] and [13]. Outlet [6] is powered by timer [11] and powers the ballasts of the white lights of the tank. Outlet [7] is powered by timer [12] and powers the ballasts of the actinic lights. Outlet [8] is powered by timer [13] and powers the air pump [10].