I was lucky enough to get some pictures of my great spider crab (Hyas araneus) just after it had molted. Now I could see it clearly. After a few days it was covbered with algae from around its favourite hideout.
Now that the light input is practically nothing there is very little uptake of inorganic nutrients. I just got a nitrate reading of 50 mg/l! What worries me the most is the phosphate concentration that is up to 0.5 mg/l. At this level it is inhibiting to calcification. This can cause harm to many of my animals. I will do some water changes, but they will not have a great effect. I guess I'll just have to hope that things improve rapidly when light returns in February. The two pictures below illustrate water quality improvements after I started using ozone.
The orange thing to the right is a small type of colony forming sea squirts are spreading everywhere in the tank's shaded areas.
There are still many species of red algae that I would like to have. Some of the nicest species don't seem to thrive in the tank. But I see some evidence of reproduction at least.