Tank DIY: Technical Details
Written by Thursday, 21 January 1999 00:00
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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.
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.
Wiring
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].
500 lit Mbuna Tank
Sometimes what lies beneath the tank (or behind it) is more important than what you see. It is the equipment which is used to keep the tank in prime shape and takes care of the well being of the fish, the plants and even controls (to some extent) the outbreak of diseases. It is said that the larger the tank the less equipment and maintenance is needed. This is true and is due to many reasons. Mainly, this has to do with the water volume which is less prone to alterations because of its much larger capacity. This is definitely true and is reflected in my two tanks; the 500 lit and the 1.300 lit. The latter is more "Spartan" in equipment and is solely based on the basics (filters, lights, pumps), while the smaller one is more "heavily" equipped.
The series of photos show the equipment used to support life in the 500 lit mbuna tank. The equipment is mainly located in the two closets at its base (see small photo). If you see all the electrical wiring and the tubing in the photos below you may correctly conclude that you need to become an electrician (after getting your plumper degree, of course). For all amateur electricians (like me) a piece of advice. Immediately after the water change, a tank like this with all heaters on, will consume more than 900 Watts. It is preferable to use two wall sockets instead of one. I learned this lesson the hard way from by 1.300 lit tank which needs 1.600 Watts. Well, it almost melted the wires in the wall before I used a second socket for some equipment.
In the photo above you see the interior of the right compartment. In brief, the numbers correspond to the following equipment. The starters for the fluorescent tubes (seven in all). The lamps are powered by a timer which is set to 12 hours. A second timer powers the air pump. This is set to start at 21:00 and stop at 8:00 just before the lamps go on. This is necessary in order to remove any carbon dioxide excess. The same timer also powers the UV lamps (see the contents of the left closet, below). Then there is the first external canister filter (900 lits / hour) which is powered directly along with the right internal sponge filter (rated at 950 lits / hour, too). All wires and tubes reach the tank through an opening in the back of the closet.
This photo shows the contents of the left hand side compartment of the cabinet. The first thing is the carbon dioxide canister which holds 2.5 Kg of it. The outlet of the manometer is inserted in the inlet of the canister filter (in the tank). This way, the gas is forced to travel a long way in the filter's tubes then mixed well in the canister and return to the tank almost completely dissolved. There is also a spare carbon dioxide canister which is filled when the pressure on the first one drops to the lower green region of the manometer. The stand holds the fishnets. Next are the two UV lamps, 8 watts each, which are connected in line with the second external canister filter. The presence of two lamps in necessary to comply with the filter's flaw rate which slightly exceeds the efficacy of one lamp alone. The UV lamps are connected to the air pump's timer and are turned on for a week every month. The second internal sponge filter is also powered from the same socket.
On the left you can see the UPS which is used for this tank. It is rated at 750W and the only things connected to it are the four filters, a total 75 Watts. The UPS will keep the filters going for 2 hours and will fully recharge in 10 minutes. In contrast, the 1.300 lit tank is equipped with a 1250 watt UPS which will keep the internal filters going for 3 hours. The photo on the right shows details of the hole in the top tank cover through which all wires and tubes enter the tank.
The photos and information given above may not give the visitor a "global" picture of what is going on in the tank. Thus, I asked the help of Takis Tsamis; he kindly made the drawings below which reveal every little detail of the tank's support system.
Notes on the diagram: [ 1 ] Wall socket (grounded) which powers the UPS unit [ 2 ].[ 2 ] UPS unit (battery backup, rated at 1250 W. This unit powers the internal 5-socket unit [ 5 ] which takes care of the whole left cabinet. Thus, in a power shortcut, the basic tank functions are not interrupted.[ 3 ] Timer which powers the two UV lamps [ 4 ].[ 4 ] Two UV lamps, 8 Watt each, serially connected.[ 5 ] Internal 5 - socket unit. All electric devices in the left cabinet is powered from this unit which is powered by the UPS [ 2 ].[ 6 ] External canister filter ( 900 lits / hour ).[ 7 ] Two timers which power the transformers of the lamps [ 10 ] and the air pump [ 8 ].[ 8 ] Air pump which delivers 350 lits / hour. The air pump is turned on during the night hours by one of the timers [ 7 ].[ 9 ] Internal 5 - socket unit. All the electric devices in the right cabinet are powered by this unit.[ 10 ] Fluorescent tube transformers and ballasts.[ 11 ] External canister filter ( 900 lits / hour ).[ 12 ] Six internal sponge filters (950 lits / hour each) located in the opposite sides of the tank. The number of internal filters varies between 4 - 6 depending on the needs of the other tanks.[ 13 ] Two 300 W titanium heating rods. The rods do not have a thermostat on them. Their thermostat [ 16 ] takes readings via its temperature sensor [ 15 ] and turns them "on" or "off" automatically.[ 14 ] Eight fluorescent tubes. The tubes are of various Kelvin ratings and colors and create a very natural, well lit, shallow water atmosphere. There are 4 common Philips Aquarelle lamps, two Ultra Tri Lux - Penn Plax lamps and two Arcadia Marine White (9500 K) ones. The total output exceeds the 0.75 W / lit mark which is the minimum for the growth of light demanding plants. During the hot summer months only 2-3 lamps are operated while the duration of the light period is also reduced.[ 15 ] Temperature sensor of the heater thermostat [ 16 ].[ 16 ] Thermostat.[ 17 ] Two small fans located just above the water surface. Very useful in the summer.
The success of any tank is primarily based on two factors: correct stocking and a good support system. The hobbyist should always keep in mind that both need the same kind of care if they are to last.
Below you can see a diagram of the flow of the water and carbon dioxide in this system. The six internal sponge filters (950 lits / hour each) are ignored since their number varies with the season and the needs of the other tanks. The presence of these filters is for "seeding" purposes (in case I suddenly have to set up a new tank).
In this diagram the main water and carbon dioxide flow is shown. [ 1 ] The carbon dioxide cylinder is equipped with a manometer / regulator system which allows for the fine tuning of the gas flow. The gas flows via a special silicon tube which reduced leakage to acceptable levels (marked red in the diagram).[ 2 ] The 2.5 Kg carbon dioxide cylinder. Its outlet is inserted in the inlet [ 6 ] of the external canister filter [ 3 ]. This way the carbon dioxide is forced to travel a long way in the water and is mixed very well in it, especially in the "pressurized" environment of the canister filter. Clean water tubes are marked in lighter blue. The outlet of the canister filter [ 3 ] is inserted in the inlet of the first UV lamp [ 5 ] and then travels through the second UV lamp before finally returning in the tank [ 9 ]. On the left side things are far more simple since the external filter [ 4 ] works with no attachments on it. Both its inlet [ 7 ] and outlet [ 8 ] are placed towards the back of the tank creating a current behind the rock formations.
A final word of caution: a clogged filter is a far more efficient killer than any disease - yet, unlike diseases, it is very easy to avoid it.
Photos by the author; drawings by Takis Tsamis.
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