February 7, 2015
Finally the plankton project, part two, is up and running! I have been planning this since the last plankton project ended, 1.5 years ago. So it feels incredible to have started, even though the project is smaller than originally planned. I had to settle on plankton aquariums only without a display tank, so far. But there are possibilities for expanding it later if things work out well. So I will not be able to test feeding rates fully, but I will be able to check if it is at all possible to grow large quantities of zooplankton with my method. The current setup has two plankton refugiums, one for zooplankton and one for phytoplankton. The phytoplankton one is a 115 liters tank with about 85 liters of water and the zooplankton one is a 300 liters tank with around 250 liters of water. For more details on how it works, see the blog on part 1.
The setup. Note: The pump that pumps water from the zooplankton aquarium to the phytoplankton aquarium was not connected at the time the picture was taken.
In my last plankton project I dosed nutrients manually once per day. This time I wanted automatic dosing for several reasons: First, it is easier to just let the pump do the work. Second, I wanted to test if it was possible to avoid crashes with almost continuous dosing. I also wanted to experiment with dosing in such a way that a minimum of nutrients left the phytoplankton tank and entered the zooplankton tank. So I looked into what alternatives there were in terms of dosing pumps. The ideal was a gro-tech programmable 4 pump. But the price tag was a bit hefty, so I looked at the China alternatives at fish-street.com. I didn't take the chance on the cheapest alternative, but Bubble Magus has a good reputation. So I went with the 3 pump BM-T01. There was only a chinese manual with it, but fish-street had a translation. The translation was really bad, and the texts on the pump display were downright insane. The translator seemed to think that the at sign "@" is an important part of the english language, because it is generously sprinkled around in the texts. But after some work I managed to figure it out, and it seems to be working OK.
Dosing setup. I try to keep the micro nutrients and vitamins shaded. They stay in the hoses for 2 days before entering the aquarium. The hoses are inside a PVC pipe when crossing over to the phytoplankton aquarium.
Evlything und@l condbol! Menu texts from the Bubble Magus BM-T01 dosing pump.
For nutrients I bought modified F/2 formula from Florida aqua farms. I bough only the trace elements and vitamins from them this time, and then nitrate and phosphate from another source since I was afraid there would be problems with shipping from the USA. I kind of regret only having a pump with 3 heads. I would like to have at least two more. I would like to experiment with dosing iodine and glucose too.
"Macro" is nitrate and phosphate, "trace" is iron, zinc, cobalt, EDTA, iodide, manganese, molybdate, vanadium, cyanocobalamin, biotin, thiamine, copper. This is called modified Guillard F/2 medium. My start dose was one tenth F/2 dose for the phytoplankton refugium per day. Except double dose silicon because I measured 0 after a week.
I decided I needed full temperature control over the individual tanks. I wanted to be able to set the temperature to anything I wanted in any tank at any time. So each tank needed its own chiller. In line chillers, that is chillers fed by pumps, can't be used in plankton aquariums. So that means that virtually all chillers are out of the question. The ice probe thermoelectric chillers that I bought are completely useless. There are a few american companies that make drop-in chillers. The prices start at about $850 I think. Then there is a major shipping issue, norwegian taxes, plus, I don't even know if they make them for european electricity standards. So buying those was out of the question too. So I decided to take the plunge and do something I have been wanting to do for some time, which is to learn refrigeration technology, buy tools and parts, and modify air dehumidifiers to drop in chillers. It took me more than a year from I started learning until I had two nice, operating chillers. It was really great fun to make them though. If they turn out to work fine in the long term I will never need to buy an expensive aquarium chiller again. How I made the chillers will be described in a separate article. I can tell you it was quite a job.
DIY drop-in chiller from modified air dehumidifier. The heat exchanger is made from 316L stainless steel. It will be interesting to see if it rusts eventually.
Chiller operating. The chiller is adjusted so that the cooling medium evaporates at a few degrees below 0, celsius. That makes ice form on the tube where it goes into the heat exchanger. Both hoses from one of the air pumps blows bubbles under the heat exchanger to create flow over it.
The chiller for the phytoplankton aquarium. Made from a dehumidifier of older design.
This is how I control the chillers, with an external temperature controller.
One air pump for each aquarium bubbles the water to provide mixing and flow over the heat exchangers.
Messing with hot melt glue to create holders for the air hoses.
Two of the insulation foam pieces can be taken off the zooplankton tank for photography and inspection.
It was such a nice January saturday when I drove out to the islands west of Bergen to fill water. My new 20 liter cans worked just fine. They have two very large openings, so filling one takes only 5 seconds. Very practical. Carrying the 360 liters around was a bit of a workout sessions though. I had to drive two times as I had only 9 cans. The car would have had room for 12 of them though.
Very practical cans bought at Biltema.
At the time of writing the system has been running for 2 weeks. Everything is working according to plan so far. The phytoplankton bloomed with the same species as last time. The crash after one week wasn't as bad as it usually is. I have been able to catch plenty of zooplankton, even though it is winter. So right now I just have to be patient and see if they survive and reproduce in my system!