Aquarist - the Regulator
Starting a Marine Tank IV
Written by Friday, 28 June 2002 00:00
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| Starting a Marine Tank IV |
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Two months later the tank is running, the major parameters (pH, temperature, specific gravity, NH3, NO2-, NO3-) are rather stable (and continuously monitored) and now it is the maintenance issue that bothers me most. Currently the tank runs without a heater (unplugged) since the heat generated by the 4 motors is enough to keep the water temperature around 26C without any major fluctuations. It may rise to 27C when the four fluorescent tubes are on (one more was recently added - a marine white / full spectrum 6500 K) and then slowly go down to 26C during the night. The lighting period has been set to 12 hours daily to promote the growth of algae on the rock. It is said that no matter how many tubes and metal halides you add to a tank the light level will never be the same as in nature. This is especially true for plants / invertebrates which live in shallow depths and my rock was collected at a depth of 30 cm! I can see the algae on it responding to that extra tube and the 2 hours of additional lighting.
It is true that the appearance of the tank is not the best there could be but this is more or less an "experimental" and not a display tank. The fish seem comfortable, they enjoy their hiding places as well as killing my prawns and displaying to each other so I guess I must be doing something the correct way.
Photo of one more shell in my tank. This particular animal was the one that acclimatized last. During the first days it used to come out during the dark period while it would vanish in the sand when the lights went on. Definitely a vegetarian (always seen either on the front glass - usually covered with algae - or on my live rock) it is approximately 6 cm in length (larger than my fish !!). When buried in the sand it will go on moving since my once perfectly levelled sand now resembles a moonscape. During the last few days it will stay for approximately 30 minutes with the lights on and then retreat to its sandy world. I think it is the perfect time for one more visit at the seashore to collect some more inhabitants.
Following our return from the seashore (a good collection day with a temperature of about 14 C and a shinning sun) it was time to acclimatize the inhabitants in terms of temperature (the specific gravity is almost the same between my tank and the Mediterranean sea). After letting the water sit for another two hours, the difference in temperature was less than two degrees Celsius, so Johnny and I started the transfer. Snails, hermit crabs, macroalgae, new prawns and a pair of blennies was the load to be added in the tank.
A good sized hermit crab in the tank. A magnificent animal (note the fluorescent blue on the thick legs), always on the move, particularly interested in the decaying algae. This animal (sized about 7 cm) became the target of the blue devil which showed me what real aggression means. I though that keeping Malawi cichlids had taught me the basics but you should see this blue fish displaying and then attacking the shell of the crab ferociously ! This went on for days ! Every time the two of them met, there was an immediate fight.
Another king of macroalgae. Since there are no corals I want to try as many species as possible to determine the conditions under which each of them thrives. This one seems particularly promising. According to Andreas Iliopoulos it is definitely a Caulerpa species (probably a C. racemosa).
Two more shells on the second piece of live rock. This piece of rock, apart from the algae and some shells, also had a true snail on it. A white, beautiful, tiny creature (about 5 mm in length) which will be shown when I manage to take a descent picture.. Its size calls for real macro photography. It is always fascinating to discover how many things lived on this small piece of rock. Every time you observe your tank there is always something new to see ! This photo was taken with the existing light. Note the blue cast although there are no actinics installed.
Two blennies were collected among the other creatures for our experimental tank. Showing a beautiful red colour they are a really interesting sight in the tank. The more they stay in the tank the more time they spend in the open although the presence of the blue devil doesn't allow them to enjoy the sand. The fish, possibly two females or not territorial males of the Tripterygion tripteronotus (Red triplefin) species, were collected at a depth of 30 cm. They are colourful despite their small size (less than 5 cm). Thanks to A. Iliopoulos for identifying the fish.
One day I was really shocked. Two of my snail-like red invertebrates (the only red ones I had) were seemingly dead. Just 48 hours after collection they had attached on the front glass and stayed there for the whole day - motionless. After 6-7 hours I saw some bubbles coming out of one of them (the one on the right in the picture below) and I was sure that this was the air from its shell.. the poor creature was dying. I thought it was probably the difference in temperature since it had risen from 12 degrees C (place of collection) to 26 degrees (my tank) in less than one day. Since I remembered that dead shells are usually found on the bottom I presumed that there was still a chance they were not dead. I am always thinking of my system as a very "fragile" one and I was worried that decaying matter from those invertebrates could poison my water but I decided to take two measurements per day and let them there for 24 hours more. Ammonia, nitrites and nitrates were almost zero so I assumed I had some time before removing them.
The next day I was relieved. The two reddies had moved apart from each other but while they moved they kept on releasing those bubbles which, despite the very strong current never moved from the glass. You could tell where the red little fellow was (or which path it had followed) by the line of bubbles it left behind.
Of course, the mystery was solved 24 hours later. The reddies were not producing bubbles, they were laying eggs. In fact hundreds of eggs all over the tank. On the filters, on the skimmer's pump (see photo), on the glass, almost everywhere, you could see clusters of eggs attached and linked to each other with fine lines. I don't know much about their reproduction but it could be possible to be due to the higher temperature which could have "reminded" them of summer and turned on their reproductive instincts. And I was about to remove them... Sometime ignorance is a really dangerous thing. I never thought I would be so thrilled by seeing bubbles in a tank !!! In the days that followed most of the eggs were consumed by the prawns which used to "walk" through the egg mass and then collect the eggs with their special feet. However, after 5 days there are still some of them in the walls of the tank, particularly on the top of the filters. Of course, hundreds of small red shells in my tank was not the reason for starting this project but it would be a welcomed side effect.
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