Coldwater marine aquarium Blog 2007 November
25 November 2007

Good news for cold water aquarists

Cooling of water is probably the major obstruction for those who live in temperate climates and want to keep native species. First chillers weren't available at all. Then they were very expensive devices made for a tiny market. Finally, thanks to the popularity of the reef keeping hobby, they are now being manufactured in China and can be bought cheaply. I was lucky enough to come across this link the other day:

Aquatics Online - Coolers & Conditioners

This chiller should be exactly as powerful as the one I use. I paid 10500 NOK (2000 USD, 1300 EURO) for mine and this one can be bought and imported for 4300 NOK to Norway (830 USD, 540 EUR). That should be under the pain threshold even for those who aren't fanatic about getting a cold water aquarium. I remember when I first decided to get a chiller for my aquarium I thought that 4000 NOK was the max i would pay. That was very expensive. 10000 NOK was just insane, out of the question. The fact that chillers now are at this critical price level could have significant impact on the whole hobby.

Here is the link to D-D, the company that own the brand for the chiller. Manual for this plus two other models can be downloaded:

DC-750 Refrigerated Cooler

A small glitch in the manual reveals the manufacturer of the chillers, a Chinese company called Hailea:

Hailea main page

Product page for Hailea HC-300A

I have a few things I want to do for the marine cold water hobby. After some years of reading posts from beginners on fora I have noticed some questions that show up over and over again. The answers on these questions are either negative or not satisfactory. Here are som typical answers regarding cooling:

I would like to show that all of these are now wrong:

The price for the chiller itself is down to an acceptable level. As for the energy cost, I am not quite sure where this idea comes from. But a chiller of 400 Watts that runs about 70% percent of the time doesn't amount to that much even if the energy was wasted. In cold climates however, the chiller works as a heat recirculation system. All energy transferred into the tank, plus that from the chiller itself is released into the room as heat. If the room is heated, like a livingroom for example, the energy is practically free because one would have used that energy to heat the room anyway. It is not free if you have a cheaper way to get heating energy, like a heat pump, but at least the energy is not wasted, just a little more expensive. A cold water tank has practically no evaporation so no energy is used to evaporate water. The smell and humidity that follows evaporation are also avoided.

You do not need a very powerful chiller for a cold water tank. The idea that you do probably comes from simple reasoning: You need a such and such chiller to cool a reef tank 5 degrees celcius. So to cool the same size of tank 15 degrees you need a 3 times bigger chiller. Sounds logical. Also, when engineers take classes in cooling they work with a volume of liquid, and a number of hours before that liquid needs to be cooled x degrees. That is also a way of thinking that leads to great numbers. Third, the efficiency of a chiller greatly depends upon air temperature. If it is placed in a small, poorly ventilated room with several metal halide lamps on a hot summer day it is possible that the air temperature becomes so great that it drastically reduces the chiller's efficiency. I'd like to turn this upside down and ask you to look at a freezer. How much of an engine does it have and which volume are we talking about? The engine is 50 to 100 watts, only a fraction of an aquarium chiller, and still it can cool 1000 liters down to -18C. The secret is that it is insulated and no energy is inputed into the system. So we should go in the same direction with a coldwater tank. We insulate it on the sides where there is no view into the tank, and use double glass in front. On top of the water surface a layer of cold air will sink down and lay still. This layer insulates the top of the tank if it is not disturbed. In winter there is very little light in temperate areas so we shorten the days and use very little light. For example, now in late November I use only 100 watts of light for 5 hours a day. I don't think my 1/4 HP (375 Watts consumption) chiller will have any trouble chilling the 1000 liters tank down to 4C. With a good design you can use a 1/4 HP chiller for most sizes of home aquaria. If you have tank under 300 liters you could go down a step. If it is above 1000 liters you probably should go up a step.

Chillers are noisy, yes. But as I show in this update there are ways to dampen the sound while still recycling the heat efficiently, and not reducing the capacity of the chiller. The chiller can of course be placed in a room that is not inhabited, like a hallway.

Condensation on the glass is not much of a problem. One of the reasons for that is that the room with the tank and chiller will not be moist like a room with a tropical tank. There is practically no evaporation from a cold water tank and the warm air from the chiller dries the room. In my apartment I have the opposite problem: The air is actually too dry. And I have a 1000 liters tank in a small apartement! The humidity is 30% and that is very low in a wet coastal climate. There is absolutely no condensation on the glass now even when the room temperature is 24C and the tank temp is 10C. According to a chart I have condensation will not form before the water goes below 5C. Still, if you are going to simulate real winter with temperatures down to say 4C, then condensation will probably be a problem for most. The heat loss through the glass could also be significant. This is where double glass comes to play. One may think that getting that for an aquarium requires buying a custom designed tank at insane prices. I don't think so. I am now trying out making this myself with just a cheap pane of glass ordered from a local glass service company. This seems to be so simple that anyone can do it. And the glass pane can be removed for cleaning just in case I missed a spot before putting it in place. It can also be removed in summer to allow better photography and more comfortable viewing.

Chiller box

Project one, the chiller box is done. It works really well. The sound from the chiller is drastically reduced, and I can't observe any reduction in efficiency.

The box was made out of white painted particle board. I cut out fitting pieces with a cicular saw and joined them with deck screws and ordinary water based wood glue. In the bottom ther is a frame out of wood to strengthen the structure.

Chiller box

Holes for three 120mm x 120mm silent computer fans.

Chiller box

"Contact glue" smeared on.

Sound insulating sheets were cut to size with a knife and glued with a glue called "contact glue". It is painted on both surfaces with a brush, then after 10 minutes the surfaces are pressed together and they stick immediately. I bought some rather expensive high quality sound dampening sheets, and I am really glad I did. The extra cost was well worth the lower sound level.

Chiller box

Fans mounted

Chiller box

The lid. In the back is the exchaust "Chimney" that leads hot air out.

Chiller box

Mounting the cable for the fans in the chiller.

Chiller box

I though I had to cut the cable to the compressor to wire the fans into that circuit. But it turned out that the chiller had a box with an electrical panel in it so I could just "plug" the fans in there without breaking anything.

Chiller box

Here we se how the chiller divides the box in two, no air passes through the box withouth going through the chiller.

Chiller box

With the lid on.


I've been experimenting a with traps lately. I feel I am starting right at the bottom in that area. And that is not only literally. The only thing I know is that you can trap animals with a transparent container that has an invard cone shaped opening. Most animals, except from mammals and birds, don't have the intelligence to find their way out of such a contrapment. So far, I've tested out two generations of such traps. I use two types, one is a crayfish trap covered with a finer mesh net and with the openings made smaller. The other is a traditional "bottle trap" consisting of a soda bottle with the top cut off and set inn backwards. The main focus is on the soda bottles for now, since they are cheapes to lose. I've lost practically all of the traps I've set so far.

The first trip was kind of funny, at least afterwards. I went to a really wave exposed site and threw a bottle trap into the water. First problem: It didn't really sink, even though it had a few small rocks glued to the inside and lots of holes. The current was extremely strong and swooshed the trap away. The fishing line attached to it had no chance, it snapped right off. I also noticed that the trap wouldn't sink with the opening down so it could be standing on the bottom with the opening up. After two more unsuccessful tries at getting a trap set I decided to call it off. The second revision of the bottle traps had 2 stainless steel bars attached to the outside for weight, real thin rope and many more holes. A new calmer location was chosen. The setting went all right, but even then I felt that something was wrong. There were waves, there was kelp. The rope got tangled into the kelp and the wave motion practically wound it up around the plants. That created a real mess since the traps were probably dragged along the bottom and out of position. The forces of the ocean are great, as many have experienced, in some cases the ropes were cut off. In other cases it was impossible to get them up without ripping them off. In two cases I managed to get up a nice bouchet of Laminaria hyperborea, but no trap. Only two out of about 10 traps were saved, one net and one bottle trap. The net trap had some wrasses in it. They were too large for me so I let them go. It was very encouraging to get some catch under such unfavorable conditions. The bottle trap had two large starfish in it. The bait obviously worked well. I'll also try non baited traps to cath other animals than scavengers.



Caught with the snout in the cookie jar!

There are lots of hitchhikers in the tank. The coolest I've seen so far is a large sea hare ( Aplysia punctata). But in second place is this large nudibranch. It is an Aeolidia papillosa . One morning when I was looking into the tank with a flashlight I saw it munching on one of the anemones. This is a specialized anemone predator. I wanted to keep it, but I didn't take the chance on keeping such a large specimen right now. The anemones a kind of stressed already. They move around alot, probably because of the reduced feeding. So I released it back into the ocean on a place with lots of anemoes for it to munch on. There are actually many species of nudibranchs in this region. They feed on bryozoans, hydroids, corals, sponges and anemones, and are specialized at eating a small number of species. I want these in my tank, but I've avoided them until now since it is best to build up a population of prey before introducing predators. But once I feel that I have enough of a certain type of the mentioned prey animals, I will try introducing small specimens of nudibranchs.


This is probably Aeolidia papillosa.

Sand goby

Sand goby

Pink shrimp

Pink shrimp

Red algae

Some red algae. I have no idea which. They are very hard to identify, and few pictures are available.


Various. The rock with light color is from the ocean and has a great epifauna/flora on it.

12 November 2007

Not much is happening with the tank itself at the moment. Low nutrients, falling light levels and temperature are keeping the state relatively stable. Most algae are growing a little. Some new ones have even popped up. I haven't been out much since I have been busy and it's dark, cold and rainy here.

Hermit fight

That hermits and crabs fight among themselves are known to most, but did you know that if a dominant hermit wants the shell from one lower down on the ranking ladder it can take it? That is shown in this rather blurry picture series. The funny thing is that the hermits are of the same size, so how do they decide who's the boss?

hermits having a shell dispute

Here the dominant one has chased the other to hide in the shell. The dominant pulls the competitor's claws and bashes its own shell agains the other. This went on for a long time.

hermits having a shell dispute

Finally the other chickens out and comes out of the shell.

hermits having a shell dispute

It runs away quickly.

hermits having a shell dispute

The victor takes its place.

hermits having a shell dispute

The loser waits nervously for the dominant one to move away from the empty shell.

hermits having a shell dispute

When the coast is clear it runs back...

hermits having a shell dispute

... and jumps in.

hermits having a shell dispute

"The switch" is complete. Friends again..?

Hermit eating snail

Not only the french like snails. This hermit is munching happily on one.

The hermits catch snails every now and then, if they are lucky and get a hold in the soft part with the strong claw. The bigger they grow the more snails they can take. It's ok, I have more than enough snails. But I consider releasing some hermits back into the sea. There shouldn't be too many large ones.

Shore crab

Shore crab (Carcinus maenas)

The same goes for shore crabs. There are constantly new individuals popping up, and they grow fast. Very active and charming animals. I have released two of these back to the wild so far.

Shore crab shrimp

This crab has managed to catch a sand shrimp. Not sure how the drama ended, but the poor shrimp probably got eaten alive, from the tail up. It's a jungle in there!

Sand shrimp

Sand shrimp (Crangon crangon)


Nice colors. The red algae on the left has grown up from nothing

Dahlia anemone

My biggest dahlia anemone. I point feed it with pieces of fish meat.

Elysia viridis

Elysia viridis Nice small snails. Very attracted to Codium fragilis

Elysia viridis

Note how they can open the "wings" on their back. Choroplast cells from the algae they eat are transported into the outer tissue layers on their backs. The chloroplasts keep producing sugar to feed the snails. Some snails carry houses on their backs. These have gardens!

Sand goby

Sand goby

Green algae

This nice little hairy algae popped up from nowhere. It could be Acrosiphonia sp.

Grey topshell

Grey topshell Gibbula cineraria


I wonder if this is Palaemon elegans or maybe Palaemon adspersus

Beach prawn

Beach prawn (Palaemon elegans)

Pink shrimp

Pink shrimp (Pandalus montagui). Very nice, but much shyer than the beach prawn. Most of the time they hide under the rocks.

Sea vase

Sea vase (Ciona intestinalis). In the upper right corner we can see Camouflage, the big marine. Part of the marine tank recon squad.

Painted top shell

Painted top shell (Calliostoma zizyphinum) Norway's most beautiful snail. I have only found one of these, but unfortunately I don't think it is still alive. Didn't get any good pictures of it.

Painted top shell

These snails have a special way of feeding, in addition to the ordinary. They use their large foot to coat the shell with a fine layer of mucus. Then after awhile they remove the mucus with the foot and digest the particles stuck to it. Needless to say they always have a clean shell.

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