Native marine aquaria are pretty scarce. Little information exists on how to be successful in maintaining healthy coldwater marine systems in domestic aquaria.

Hopefully this record of my failures, triumphs and ideas will assist others interested in keeping some of our fascinating, beautiful and often little known sea denizens in aquariums.

Thursday, 7 July 2011

July 2011 Update

Its been a year since a water change was last carried out and little has changed. I switched off the skimmer a couple of months ago as no foam was being produced. The feeding has been extremely light, one small cube of artmis shrimp every 3 or 4 days.
The lights are over a year old now and the output has decreased significantly. This has caused a slow-down of macro-algal growth. As a new set of flourescent bulbs costs about £160.00 I have been looking into another alternative. I am experimenting with 'white' LEDs, a standard bulb costs about £20 for a dimmable LED in the right sort of spectrum - 5600K, non-dimmable are cheaper. The light is still a little warm and actinic flourescent T5s are needed as well. I havent been able to rig up a permanent new lighting set up on my existing tank due to a lack of time but have built a small prototype of six lamps which does create a very pleasing effect similar to halides without the heat!
So, today I have emptied the aquarium and ordered a new 1.8m L x 0.75 W x 1m wide acrylic aquarium, I'm collecting it on Tuesday from Hampton Court Flower show where it is currently forming part of a garden display. I will drill a 2" hole in the base and fit a weir which will carry the water to my old 3' tank below.
The inmates of the tank are currently in a 100 gallon cold water plastic 'roof tank' in newly collected seawater. I will move them to the sump tomorrow with all rocks but none of the sand substrate currently in a number of buckets. When the new tank is in position and plumbed in, the rocks and substrate will be introduced and a 6" layer of fresh substrate laid on top. New chalk base rock will be collected to add to the existing rock and the whole system will be topped up with further fresh seawater. Finally the inhabitants will be introduced to the new aquarium from the sump by next Thursday (hopefully!).
This weekend I will build a new hood from plywood housing around 60 LED lamps on 3 timers, the dimmable lamps will be at each end and will come on a 'soft start' programme, the centre section of 40 lamps will come on when the dimmable lamps are at full power. Hopefully this will cause less stress to the inhabitants than a sudden full-on switch on of the lamps. The T5 flourescents will come on a seperate timer a few minutes after the central section to hopefully produce something like full daylight power. I believe that strong lighting is essential for keeping shallow native marine reefs.
The existing tank will be the sump, this will house the skimmer and the return pump as well as the pump to the chiller. I will probably lay a coral sand substrate and a number of chalk rocks, this should act as a buffer for maintaining water hardness and also stabilise clacium levels. Usually I would keep this under 24 hour lighting but to avoid blocking up of the fine tubing to the ciller and also the intake of the skimmer, the sump will be dark. No algal growth should prevent the problems that have plagued my original set-up.
However, as I am such a strong advocate of some kind of refugium/algal tank as a way to naturally filter the water I will install a smaller aquarium above the new display tank with 24 hour lighting to encourage algal growth. This will be fed by the sump return pump and will overflow into the display tank. It is hoped that this will be a breeding gound for creatures that will fall into the main tank and provide zooplanton as food for the inhabitants.
Once the system has stabilised I look forward to collecting new inhabitants. Many of the creatures from last year have since outgrown the tank and have been subsequently released. The spider crab grew to a monster that decimated the hermit crabs and snails, he was released back to Kimmeridge in May. Curently only 1 corkwing wrasse reamins and 1 small spider crab that must have came as a hitcher on a rock, at 1 1/4" he is still reef safe, but will probably be sent back to the sea in the autumn. I have many anemones, both the snakelocks and the beadlet have reproduced with numerous offspring.
The addition of a sump and new LED lighting should solve the problems that the original system suffered from - deterioration of lighting strength and clogging of skimmer and chiller intakes. An overhead refugium will be an interesting development, this will probably not be possible in most set-ups but my office has a high ceiling and will allow a further tier.

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