November 6 2011

Two months of production

Last month I went on a vacation to Egypt. I could not dose nutrients then, so when I came back the phytoplankton growth in the refugium had stopped. But when I left the refugium had produced phytoplankton continuously for two months. So I am very satisfied with the phytoplankton now.

Crashed refugium

Crashed refugium after I came home from vacation.

Pollachius virens

I had only one freediving trip since last update. We were swimming in large shoals of saithe (Pollachius virens) in Øygarden.


On the zooplankton side things are not that bright. None of my experiments have succeeded so far. All zooplankton disappear after awhile. Only a few mysids and shrimps survived for a long time in the refugium. I don't know why they disappear. The obvious thing to assume is that they are washed out. To test this hypothesis I needed to place a net filter in front of the overflow so that no adult copepods could pass through. I found a fairly simple solution made from an aquarium net. It may be necessary to do some testing to find a net with the right size holes. If the hypothesis is correct and adult copepods can surive for a long time and reproduce, then it is possible that they gradually increase in numbers and at the same time feed large numbers of nauplii to the display tank. A nice theory that is definitely worth testing.

Zooplankton net

This is to stop large zooplankton from going through the overflow. It clogs fast by being overgrown with algae, but it is very easy to take out and clean every few days.


In early October some of the hydroids in the system sent out a lot of medusae. Basically the hydroids have a complex life cycle that includes a stage as medusae, free swimming jellyfish. The jellyfish then release egg and sperm cells that mate and become larvae. The larvae swim to the bottom and grow into polyps. I could observe lots of tiny jellyfish swimming in the refugium. After about two weeks they disappeared.


The diameter of this medusa is 1.5 millimeters.


A few display tank pictures

Notice all the barnacles on the right wall.

The corals have their polyps in. Maybe it is the lack of zooplankton that is the problem.

In the background you can see some new rocks that I recently added.

I've added a number of anemones lately.

These small white polyps recently appeared.


Just a few photos from my vacation in Sharm El Sheikh, Egypt. The Red Sea was fantastic as always. It is really like swimming in and endless reef aquarium.

Chromis. I love them, if I ever get a reef tank a shoal of chromis is a must. If scared they will immediately seek refuge among the coral fingers.

This wrasse was almost tame. I wonder if it was used to getting food.

Bluecheek butterflyfish. Always hovering in pairs.

Parrot fish

I like this picture. Notice how the parrot fish is just about to take a bite from the rock. It has incredibly strong teeth that it uses to bite off pieces of coral and live rock to digest the algae and other life inside. There is a loud snapping sound as it breaks off the piece. When you swim over the reef you can hear such snapping every few seconds.

This is from the lagoon near my hotel. It was full of different fish, most notably a great number of puffers that were probably digging for clams and snails in the sand.

This gorgeous little guy is guarding his cave.

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