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.

Sunday, 31 July 2011

July in Cornwall Collecting Expedition

I have just returned from a week in Cornwall collecting new specimens. I collected from four locations -
Fowey Harbour - approx 50 2 spot gobies, 1 Goldsinny.
Wallace Beach, Looe - 3 mackeral fry, 75 periwinkle, 3 juvenile Ballen Wrasse, 2 brittle star, 1 beadlet anemone.
Porth Mawgan - 14 Sprat (?) fry, 1 Strawberry Anemone, approx 100 mussels, 4 dog whelk. Treyarnon Bay - an amazing beach, fabulous deep rockpools - 1 Lesser Sandeel, 1 Shore Rockling, 3 Golden Mullet, 1 Spiny Starfish, 1 Montagues Blenny, 1 tiny Shanny, 1 Warty Anemone, 2 Sprat (?) fry.
I kept the animals for up to a week in a 60 litre 'really useful box' with an airstone and carried oput daily water changes. I fed them on frozen garlic enriched artemia. All fed well and there were no casualties! It took 3 1/2 hours to get home and there were no motalities during transit.
All are now installed in the aquarium and have settled in well. They are feeding and seem to be behaving naturally. I originally intended to collect about 6 2 Spot Gobies, but wherever I found them they occured in large shoals so I decided to collect 50. Male to female ratio is about 1:2. They were exceedingly numerous, I fished for them in one spot only and I would guess that there were many hundreds along a sea wall only 30 feet long.
I wasnt sure about the Spiny Starfish - but my wife and children loudly convinced me! If it proves too destructive I'll release it. Its about 10" across and according to all literature I could find on it is a voracious predator! I'll offer it frozen mussels and clams, hopefully that will reduce its grazing upon my live mussel beds.
I found a crab net baited with squid to be the most effective way of catching fish, all the gobies and the Goldsinny were caught using this method.
The Shanny was an unintentional catch, we caught many dozens of shanny at all locations, however, I have found them to be too destructive to barnacles, snails, hermit crabs and prawns to be desirable as captive reef inhabitants. I didnt even see it til we got back to Bournemouth, my 6 yr old son proudly claimed to have added it to the bucket! Its about 4mm long and unlikely to be a problem for a while yet.

Monday, 18 July 2011

Lighting Considerations

I am at the design stage of new lighting for the new tank and a number of considerations are becoming apparent. Tropical reef tanks largely utilise light at the blue end of the spectrum, many reefkeepers seem to use lights in the 10000 - 20000K range. Stony corals seem to thrive best under these conditions and undesirable algal growth is inhibited.
However, in a temperate reef, algae is far and away the dominant natural feature. Therefore it seems likely that warmer lights are required. Natural sunlight is in the region of 5600K. This casts a yellowish light within the aquarium that isnt as attractive as the cooler higher ranges.
If we take 'white' light at 5600K and pass it through clear water the red end of the spectrum is effectively filtered out within 15metres. It might follow, therefore that unless we are collecting plants at depths greater than 15m we need to provide full spectrum white light.
I have built a temporary light hood, its a plywood board 1600mm long by 400mm wide. I have fixed 8 no. 3 light spotlight fittings from B&Q and fitted 15 no. 'cool white' LEDs and 9 no. 'warm white' halogen lamps (supplied with the spotlights). I understand that the cool white lamps are in the region of 7500K and the warm white lamps about 4500K.
The overall effect appears very natural with a pleasing 'ripple' effect. Although designed as a temporary measure to get some light into the tank whilst waiting for new lights to be manufactured I am beginning to wonder of these may be adequate for the job. To be honest its primarily down to cost:
new LED light panel - 450 W £1000.00
my own light panel of 24 lamps, 15no. @ 7W and 9no. @ 50W has cost £480 so far. I paid £20 each for the LEDs, double the usual cost because they are dimmable. However, I can return them for double the amount of non-dimmable ones. The cost of a LED GU10 bulb is £9.00. I would need 64 to acheive the same amount of power consumption as the manufactured LED panel. At 50W equivalent output that is 3200 Watts of light into the tank!
There are pro's and cons for both. The manufactured panel has an output of light that I cannot replicate using spotlights, I simply could not fit 22 of the B&Q fittings over the tank. It has built in cooling and uses LEDs of a known fixed colour temperature. A mix of cool white, blue and red lamps of a ratio of 25:10:10 respectively, of 45 10W LEDs should be both aesthetically pleasing as well as giving light at the corect spectrum for macroalgal growth. However, if any LEDs fail I will be unable to replace them easily - each is individually soldered.
My home-made hood allows easy changing of lamps. It is likely that better, higher output lamps will be available over time. GU10 fittings are readily available and available in blue, cool white and warm white.
I could fit another 18 lamps on my hood. An extra 6 spotlights at £9.00 each (each has 3 lamps) would allow a total of 42 LED GU10 lamps at equivalent 50W output giving 2100 W whilst consuming less than 300W. A mix of cool and warm white with maybe 3 or 4 blue should come somewhere close to giving the right result. The cost would be 24 spotlights at £9.00 each and 42 lamps at £9.00 each a total of £594.00, about 60% of the cost of the manufactured panel with 2/3rd of the output, no built in cooling and a bit 'Micky Mouse'!
Obviously the manufactured panel is going to be better. Its just the outlay.
I've added some rocks with macroalgae growth and placed them under the lamps. I'll give it 2 weeks and see how they fare before making a decision.

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.