Mather answers some questions on sand beds plus the usual features.

Editorial

Wow, times flies when you are having fun. Here I am attempting to get this on-line a couple of weeks late, opps ;-) Well, if it is any consolation, I have already started on this months, so may be I can get back on track here.

When I was down collecting natural seawater from the bay for water changes I went for bit of a stroll along the rocks as it was low tide. OK, I know that is not the best time to collect water, but it was the only time I could get down there. There were a couple of rocks that are normally submerged and they had some very nice, thin "leafed" green algae growing one it. What a perfect supplement for a tang, the The Shadow (Sailfin Tang, Zebrasoma veliferum) absolutely loved it. I placed it in the center of the tank in the open sand area and really spooked most of the fish out of their mind. They were not too happy with having a long, green, swaying think in the middle of their swimming area ;-) But after a couple of minutes they got use to it and within the hour The Shadow had started to take some nips at it. Each time he would swim past he would take a bite. On top of this there was a little bit of finer micro algae on the rock around the base of the macro algae. A couple of lucky snails found this and by the end of the day the rock was clean. The Shadow took a bit longer to get the macro algae eaten, but by the next day there was only a bare rock left. I will make sure next time I am down getting some water that I pick up a rock or two, it makes for perfect supplemental feeding.

I did not notice it at the time, but there was also a snail about 2 centimetres across attached to the rock the macro algae was on. So in she went into the hot tropical tank :-O ..... and do you think she would just curl up and die at such elevated temperatures? No, she would not do that, not even when the water is 10^oC hotter than where she normally lives. I was suspecting it to may be cruise around for a week or two at the most before going shell up, but I have been pleasantly surprised. She appears to be very happy and is as just as good of an algae eater as any of the other snails that have taken up residency in OZ REEF. It will be very interesting to see what happens in the long term, specifically if will survive the elevated temperatures. If so then I will be tempted to pick up a couple more next time I am down at the beach.

Have had just a little bit of fun with my calcium reactor over the last month or so. Thinking I had it set correctly it has been churning away for a month or two with too much carbon dioxide going through it :-O This was indicated by the fact the tanks pH was being depressed while the alkalinity was still at a suitable level. So once I woke up to this all it took was a couple of valve setting alterations and things are now perfect. The carbon dioxide is bubbled in at about 80 bubbles per minute, though this is rather hard to estimate even with the bubble counter I have. The bubbles tend to go in bursts, then a lesser rate, then another rapid burst. This is due to the regulator causing slight fluctuations in the pressure. And the water flow rate through it is now set at around 2 litres per hour. After a couple of weeks I will retest everything and see if this has to be re-adjusted, just to give things plenty of time to reach equilibrium. Calcium is back up to just over 400ppm last time it was tested, which I am very happy with, as it had dropped to around 300ppm previously. I am now slapping myself, wondering why I did not realise this to start with .... oh well, we learn something new everyday ;-)

I think I have previously mentioned one of the Acropora sp. colonies that stopped growing at the tips after a short growth after being put into the Park. There are four branches that suffered from this. I accidentally broke one of the ends off and within days it had started to grow and has continued to grow since. It appears for some reason that the terminal polyps have lost their desire to grow, very unusual. All four have now been snapped off and all are growing nicely. As an experiment since the tips were not growing, I placed the tip down into the epoxy putty to attach it to some rock. I wanted to see if the original "base" would start growing. With the two of the fragments they were wiped out in about 1 and a half days, with one surviving 3. No new growth even seemed to take place that is normally seen at the top of a fragment within 24 hours. This is by no means conclusive, but I am going to try this again some time with some spare "healthy" fragments and see if the same occurs. Rather interesting observation anyway.

A couple of months ago I purchased the equipment to add another 2 40 Watt fluorescent lights to the current lighting. Finally I got the spare time on a weekend to add these. The idea was to add more blue light through the use of actinics and increase the total lighting power. Although the power has not really been increased that much, a 13% increase from 550W to 630W, but it was mainly to increase the light intensity during the morning and evening when the metal halides are not operational. As bit of a consolation I substituted one of the actinic globes with a daylight, a blue tank gets just a little too hard on the eyes to look at ;-) At the same time I also replaced the current actinic globes with new ones, 18 months since they were installed.

While on the topic of lighting, I just picked up new MH globes, as the current ones have been in operation over the Park for over 18 months now. They were going to be replace, but I started thinking about the total operating hours the globes had been in use. If you assume that the recommendation of 12 months for a globe, with 10 hours of operation per day, that works out to be around 3,600 hours in operation. On the other hand due to the way my metal halides are in operation during the cycling period, the gradual ramping up, and current usage they have roughly only been in operation for about 2,700 hours. So this is way below their "useful" operational life. Because of this I plan to keep the current globes in operation for another couple of months, may be up to 6 months. Although the globes were nicely prices, only AUD$65 each for 250W 6,000K. It is always a good idea to go to a lighting specialist rather than an aquarium store ;-)

And lastly just a reminder if you are looking for DIY details of almost anything, then check out the DIY Plans section. I have been adding regularly to the list of plans I have found elsewhere on the WWW, and there are some new ones of my own design too. Hope you find them useful.

Thats all for this month,
Catch ya,
DBW

Welcome OZ REEF's New Residents

• 2 x ????, Purple Sponge. A brilliant coloured, bright purple sponge, but just did not want to take, see the Bereavement Notices for full details.
• 1 x ????, Pink Ball Sponge. Very nice sponge in the shape of a water drop, with a real pink colouring and about 4cm across. It has settled in nicely, with no noticeable die back. Although have not managed to find a spot for it to settle into, it is just a sponge and is not attached to any rock.
• 1 x ????, Red/Yellow Ball Sponge. Some of the things you find in the bottom and back of store takes are really quite amazing, and usually free ;-) This is only about 1cm across, so is rather small. One halve of the sponge is a red colour which then fades into yellow on the other side.

Resident of the Month

Dear Marther ReefKeeper

Dear Marther,

I am currently in the midst of the planning of a reef and are looking for some input on the use of sand as a substrate. What is your current thinking on use of sand beds in a reef aquarium? What grain size is best, how deep should the sand bed be, should I use live sand or let the life from the live rock populate it, how much sand to live rock area, sand sifters etc? Thank you for any advice and comments.

From,
Plen Um

Dear Plen,

Sand beds appear to be undergoing quite a change currently, and this has been occurring for around 5 years. It was once considered that it was bad to have sand on the bottom of a marine aquarium. But this has now changed completely and a deep sand bed is seen as being vital for setting up a stable, complete reef aquarium.

For the sand used in the sand bed, you want a good, wide range of sizes. From a several of millimetres across, to the sugar grain size, and even finer i.e. almost silt. The reason for the variety of sizes is that it helps to better simulate wider natural conditions that the sand fauna lives in. It is the grain size and the size of the spaces between the grains that dictates the type/size of fauna that lives in it. Also, you want as much of the fine stuff as possible, more than what is typically used. "Oh no, are you telling me to use the really fine, sugar grain stuff that will go anaerobic?" Yep, I certainly am, but it wont go anaerobic if you do it properly. An anaerobic sand bed is anaerobic because it has been set up incorrectly. All techniques work, they don't work when it is not applied properly. Most of the sand currently use in reef aquariums is coarser than what is found around a reef, and this is what the organisms are adapted too. Finer sand also allows better establishment of the concentration gradients that form in a sand bed. This will be especially important if you have a thin sand layer.

Less than 5 centimetres of sand depth and you might be struggling to get anoxic conditions at the bottom. But the thickness you use is determined by what you want to achieve with the sand bed. Something the adds to the look of the aquarium, sand for the sand stirrers to play in/feed in, zone for denitrification, or an other ecosystem niche for more organisms to live in? As you go through the preceding list, increase the sand thickness and fineness (roughly as a guide, though possibly the last two could be exchangeable).

If you can, get some live sand and it to the reef system. From a supplier is usually the way, but even a sample from other tanks is better than nothing. Allowing just the fauna from the live rock to populate the sand is not really a good idea. The organisms that live in live rock do that, they live in live rock. They are not suited to the conditions present in the sand bed. There will be a few species that will colonise it, but that is not what you want. For the live sand, try and get as many different sources of sand fauna you can get. Live sand, detritus kits, sand from the bottom of a store or collectors tank, sand from the bottom of a friends tank etc. To have a good stable reef tank you want to pack as many different species on each level of the food web and niche present in the ecosystem. The more species on each level, the more stable the system is. Using some good live sand will introduce the right organisms and get you well on along this path. You don't have to add all live sand, just use a seed. Make the live sand seed as large as possible, as this will make the chances of more different species greater, and improve the chances of them establishing themselves by providing a larger number of specimens. Something around 10-25% would be a good range to aim for.

Once you have added the live sand, you have to give the organisms time to establish themselves. If you add sand stirrers straight away then they have very little chance to set up stable populations. Sand stirrers stir for a reason, they are after food, and that food is all those organisms that you spent a lot of money for in the live sand. You just purchased a very expensive meal for your sand stirrers ;-) 2 months wait is good, with 6 months being even better. Most people cannot wait that long, but the longer you wait the better things will be off in the long run.

I would also suggest that you first add the sterile sand into the tank, and don't make it too thick too fast. Otherwise you can run into problems with hydrogen sulphide production when areas go anaerobic, though this is not always the case. Give it a couple of weeks to settle down and establish the diffusion of oxygen through it. If you like you can stir it up by hand regularly too if you are too worried. The reason is that if you add some live sand or something that contains excess nutrients of some sort then diffusion or transport of oxygen to those spots can be too slow. This is because it is used up at a higher rate than which it can be transported there, via diffusion and disturbances due to sand fauna. In an established sand bed this is not a problem, things have been given time to come to equilibrium. Remember good things happen slowly. Put the live sand seed on top of the dead sand bed. Don't put it down too thick, as it is most like that there will be excess nutrients and die off that occur when it is added to the tank as indicated above. Many of the organisms will be stressed by the transportation process and then being added to your system.

In your choice of sand sifters, I would go for ones that are smaller and turn over only the surface of the sand. Cucumbers are good for this, and some types of starfish or brittle stars are not too bad either. I am not saying no sand sifters, just no heavy, over the top sand sifting. By this I mean that the entire sand bed is not turned over in one day as can be the case with some larger gobies in a smaller tank. You want the sand fauna you spent a lot of time and money into coaxing into the sand to multiply a chance to have a sustainable population. Heavy predation by a heavy sand sifter is not going to allow this to happen. Cucumbers are fine, because they are relatively slow and only disturb the top of the sand bed.

When you are setting up the system plan ahead with the rock arrangement. As much free sand area as you can get is what you want to aim for here. Place your rocks so that only a small part is actually in contact with the base (aquarium bottom or supports, which ever you end up using) and therefore the sand. Build a nice open structure (not just the top, but down to the base too), it improves circulation and gives a much more attractive and functional structure. The number that is quoted though, which is for the Jaubert technique is 75% free sand area.

A sand bed set up with live sand and left to develop its fauna populations become a very interesting thing to explore. It is also very important part of the entire nutrient cycling within a reef ecosystem.

I hope this is helpful in your planning of your reef, best of luck with it.

From,
Marther ReefKeeper

Special Feature

Sorry, no Special Feature for this issue, but there are several in the pipe line.

You Wouldn't Believe It!

..... that soft corals, or Alcyonarians, are extremely difficult to identify accurately. Relatively little research among the coral experts of the world have been conducted on soft corals. Identification of some species is virtually impossible, with some families in desperate of re-classification. Although a very powerful identification tool is the sclerites or spicules distributed throughout the coral tissue. These are small structures formed from calcium carbonate and can take on a wide variety of shapes.

..... a new polychaete worm species, Hesiocaeca methanicola, has been discovered that lives in one of the most unlikely places .... a dimple in methane hydrate ice. The worm was discovered at a depth of 700 metres in the Gulf of Mexico, populating a rather large piece of methane hydrate that had protruded through the sea floor. They have plump, pink bodies that are fringed with pink "paddle" feet and tufts of long white bristles. Methane hydrate forms only under very high pressure and low temperatures, and is a crystalline mix of water and methane. The 700 meter depth and water temperature of 6^oC means that the methane hydrate is right on limit of its stability, all it takes is a small increase in the temperature and the ice disappears in an explosion of bubbles. This instability is used by the worms to create a home. By moving water with its feet over the ice surface a worm can generate a current powerful enough to create a dimple in the surface. With enough time this can be turned into a pit, then a tube. So, what do the worms feed on in this incredible environment? Bacteria have the ability to extract energy from methane and use it for the synthesis of organic materials from inorganic raw materials. Many other worms have been found to carry such bacteria in their gut to provide them with organic food stuffs, but this has not been found with these worms. Although bacteria has been found in their gut and some unidentified species growing on the hydrate, so they are feeding on bacteria. It is possible they maintain a "farm" of bacteria in their hole and feed off this. The ice instability also means that the worms must have a method of finding new homes when one becomes unhospitable, and this is currently unknown. (Source: New Scientist, N^o2144, 25^th July 1998)

Bereavement Notices

????, Purple Sponge
Have been attempting to get a fantastic coloured sponge to take hold in the Park, but to no avail. The sponge is just an absolutely fantastic bright purple and is growing nicely in a local stores stock tank. Firstly one single colony was introduced, but within 24 hours had started to die off, and within three days the entire colony was dead. Not a nice sight to see. I was then prepared to give it another try, may be acclimatation was too fast, or it was exposed to the air. So some pieces that were spread out over a rock were introduced and I removed one and placed elsewhere in the Park in a low light, high current area. But to no avail, the same thing occurred. It seems that conditions are just too different for it to take that shock of moving. It is also most likely that the stores tanks are much better suited to such a filter feeder with the high bio load that is present.

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