January 4 2012
The plan was to empty the refugium in early December, as soon as I got the chillers and drill bits. But I noticed that the refugium, which had by then run for 6 weeks, was getting nicer and nicer. The harpactoid copepods were really multiplying by the thousands. They did a fine job with cleaning the walls of algae. I could see a mysid swimming around carrying eggs. The soft corals in the display opened up their tentacles. So I decided to let it run just a bit longer. At the end of December all the macroalgae were gone from the walls and I could see swarms of copepods even swimming around in the water column. I did one measuring of the food value of the pods. I held a liter cup under the overflow outlet and filled it. I then filtered the water through a 25 micrometer mesh so that it was reduced to 46 milliliters. From that sample I counted the number of specimens in 4 single milliliters by dripping from a syringe onto a microscope slide. There are certain possibilities for errors in this method so I need to do better tests before reaching conclusions. But the estimate was 16000 adult individuals per day. This could amount to about 2 grams, depending on actual size of the copepods, which I did not measure. Unfortunately, there are potential errors that could lead to completely wrong results here. So if I go the route of benthic copepods, better tests are needed in future experiements.
It was hard to get pictures of the less than 1 mm copepods with the macro lens. But here you can see copepods swimming freely in the water plus a number on the 16 mm PVC air tube. The tube was actually completely covered by algae, but at the time of this picture the copepods were more than half done with eating it away.
Another attempt at a macro shot.
Measuring number of copepods per day: The liter measure was filled from the overflow and filtered trough the net into the beaker.
Measuring number of copepods per day: You can see the copepods and other debris in the beaker. From the syringe 4 milliliters were put on the slide, drop by drop, and the contents counted. Only adult, or almost adult copepods were counted. I made sure to shake and turn the syringe before each drop.
I bought two Ice Probe chillers from Marine Depot in the US. The shipping was expensive, but the chillers themselves were quite cheap. I only planned to use one and keep the other in reserve. I was thinking about using a power supply from an old PC to get 12 Volts to it. But it turned out that the power supply that came with it could handle both 115-230V and 50/60Hz. So all I had to do was to equip it with a european plug. I installed it in my little 30 liters test aquarium to see how it worked. The aquarium had no lights or pumps and it had double glass on one long side and insulation on one short side. Still the chiller could only pull the temperature down 4C when running continuously. 50 Watts of cooling is very little in other words, if the chiller even has that much effect. So this chiller has very limited use. Still, I optimistically installed it in my refugium during the last days of December. To my disappointment it only cooled the water 1 to 1.5 degrees when running continuously 24 hours a day. I had the option to install the other one too, but it was not very tempting as it would double the noise, probably without giving a lot of cooling effect. I did two other tests to reduce temperature: One was to take the air for the air pump from the outside, by placing the pump in a vent. The other was to insulate the refugium better. None of them helped. However when I reduced the temperature in the room where the refugium is placed, from 22C to 17C, the water temperature immediately dropped. So I am now able to get around 13.5 C, which I am happy with. It is possible that thermoelectric chillers are more sensitive to warm side versus cold side temperature differences. I may examine that closer.
Testing the Ice Probe Chiller.
Making a hole for the chiller in the refugium.
Hole has been drilled. Notice that there is an acryllic plate that has both been clamped and pressed to the underside of the hole so that the glass won't crack as the drill bit comes through.
The Ice Probe chiller required a hole of 1 and 1/4 inch, that is 32mm. I only had a 30 millimeter diamond hole bit. At my local stores they cost from 350 NOK, which is about 45 Euro at the time being. So I decided to take a chance and buy from the cheap online diamond tool store THK Diamond tools. It has been recommended by many. I ordered all sizes that I could ever need. It went just fine, they arrived after about a week. I can't really tell if there is a quality difference compared to the expensive one that I have. I have inlcuded some pictures for those who may be interested. I drilled two holes with the 32 mm and did not suffer any problems.
Bits from THK Diamond tools
Here I compare two 30 mm diamond drill bits. The one on the left costs 30 NOK from THK, and the one on the right costs 350 NOK from a Norwegian tile shop. The material is thinner in the THK one. The expensive one has a larger work surface that could give lower wear on the exposed parts, I don't know. I did not notice any difference in use. For aquarists, cheap is clearly best, since it gets the job done.
THK to the left.
Most of my clams are doing fine, except the sand dwelling ones that died in the start. It is easy to see because if they died I would be able to see the empty shells. My impression is that the sea stars are also fine. The anemones, hydroids and corals I am not so sure about, but apart from aparent lack of food I haven't noticed any signs of problems. The sea squirts on the other hand are clearly showing signs of problems. The growth of all species has been low. The most hardy ones are the pink sea squirts (Ascidia mentula). Most of them have survived, but with little growth. I have lost many of the Ascidia virginea, which is sad because they are the most beautiful ones. The hardy sea vase (Ciona intestinalis) reproduces and pops up here and there, but most die at young age and none have become really large. In addition I have at least 5 other species that are showing the same signs of high mortality and little growth. The only hypothesis that I can test is the one that high gas content and bubbles in the water are causing some problems with their sensitive filter organs. I am testing it by reducing the flow through the skimmer so that there are little micro bubbles in the water.
Here are some macro photos taken with my trusty old 60mm Canon macro lens.
It would be great if I could get these anemones to grow as they area absolutely fantastic looking. The orange one is plumose anemone (Metridium senile). The other is some Sagartia species. A dead sea squirt (see comments above) can be seen to the right on the rock.
This colony of blue mussels (Mytilus edulis) is really amazing. It contains around 50 specimens. All of them have entered the tank as larvae with water change water or in some other way without me knowing it. They popped up in various places and have walked around until they found each other on this particular spot. Not bad for animals that don't even have brains.
Plumose anemones (Metridium senile).
I have many of these small filter feeding worms. The fans are about one centimeter in diameter. They are all brown-grey in color, except this guy. He decided he wanted to be different. So he became bright blue. Weird.
Pink sea squirt (Ascidia mentula). Inlaid is the same specimen in May. It has changed shape and color somewhat, but it has not grown much.
Brittle star (Ophiothrix fragilis) feeding in the current.
One of the dead man's fingers corals (Alcyonium digitatum) has its polyps out.
A nice color morph of brittle star (Ophiothrix fragilis).
Oyster (Ostrea edulis) covered in brittle stars.
Unidentified sea squirt. It is hanging in there.
Just some photos from trips including a dive on new years eve. I was afraid it was going to be cold in the heavy wind and 2 degrees Celsius, but once we got into the water we couldn't really notice much difference from summer. And the visibility was much better even in the weak light. The water temperature was still 7.5 degrees. We collected a large crab and some scallops for food. I found a number of sand dwelling brittle stars (Ophiura ophiura). So now I have 4 species of brittle stars in the display.
Edible crab (Cancer pagurus) with enormous claws. Sadly it had just molted so there was little meat in it.
I will now test both phyoplankton growth and zooplankton growth under the new temperature regime. That will take a few months. In the meantime I will hopefully do a lot of freediving, and perhaps find some new species.