Short issue, with Martha explaining the techniques that can be used to replacing evaporation water.

Editorial

Hmm, I was just thinking, about 4 weeks away it will be 1 year since OZ REEF came into being. Wow, it does not seem that long, but also it seems like I have had the tank for an eternaty. I cannot really think of what it was like before, I wonder what I did with all my spare time ;-) I don't really have much to say this month, not a real lot has been going on because of Christmas, holidays etc.

The most newsworth happening would have to be ..... oops, no it would not, something much more important than that ;-) I have just downloaded about 16 new pictures, and they can all be seen in the Postcard Tour. I particularly like the one of the Valeniennea puellaris, nice angle. Anyway, check it out, and let me know what you think.

What I was about to say was that I was away for 6 entire days. And in that time nothing at all went wrong, no fish died, pumps/heaters did not fail, evaporation make up water did not run out. I was really impressed to walk into the room, and see the entire Park as I left it. The only things were there was a bit of algea on the front glass, as I was not around to clean it off, and the orange spotted gobies had move the sand around as usual. Things must be going along well :-)

Recently quite a few people have been asking the thickness of the sand on the bottom of OZ REEF, and I have really only been guessing as I have not measured it since I put the live sand in. So, out came the wooden rule. The sand bed height varies from a minimum of 40mm up to 100mm, and even 130mm in some spots due to the gobies. The minimum is where the gobies have dug down through the sand to the eggcrate, and I am now very glad that I have that in there. As an average over the entire tank it works out to be around the 80mm mark. So I suppose you would call it a fairly thick bed of sand, and I think it is working too. Nitrates are to a nice level, and the gobies have heaps of sand to keep them happy and fed.

A couple of mornings ago, about 2 hours before the lights go on, I was looking around the Park with a torch. I spotted some rapidly moving objects that appeared to be the usual worms that I get every now and then. I kept the torch stationary for awhile, and they were attracted to the light and soon had quite a group of them. Turning off the circulation, and using a bright light, I managed to concentrated quite a few of them, about 15-20, and siphoned them off and placed them into the larvae tank. The larvae are about 3-4 mm long, 1.5mm wide, with a slight wedge shaping. They can swim very well, zipping around in the currents without much effort at all. The eyes are very prominent, being black spots, and the body remains almost dead straight as they move. One side of the back half of the body appears to have similar features to a shrimp, hmmm I have no idea what it is called etc, but the under side of the tail, which beat to help them to move and aerate their eggs. That is the only other features I could spot. There are no noticeable claws or any other limbs, but they could just be really small and fine.

With no noticeable claws, that rules out being L. amboinensis as they have hatched several times previously and look like a miniature of the adults, claws and all. The tail features rules out being V. puellaris, and their fry move in a spurting fashion. Other than that I am at a loss at what they could be. I don't have any other crustaceans that I have added to the tank, save a single L. debelius that might or might not be alive (have not seen for months, but that don't mean much with these dudes). The fry did not last the entire day until I got back home, which is a shame. Anway, if anyone has an idea of what they might have been, then please contact me As I said about I have no idea what they were, save some sort of crustacean/shrimp because of the tail.

The new resident this month is a Galaxea fascicularis , and the sweepers they form is really quite incredible. I was yet to see one of these in person until I brought it home. The sweepers come out about 1 hour after sundown, and retract again about 1 hour before sunrise. So far they are up to about 60mm long, which is a world of difference from the tentalces around the polyps which are only about 5mm at the longest. They are also very fine, with a bulb shape at the end. Will have to keep an eye on it at night every now and just to make sure it is behaving itself.

Well, that is it for this month. Catch ya,
DBW

Welcome OZ REEF's New Residents

Another very quiet month on this side of things. The quaility and range of stock around has been very low due to the holiday season and cyclones on the Great Barrier Reef that have hindered collecting.

• 1 x Galaxy fascicularis, Galaxy coral. I have always wanted one of these guys because they look very nice, all the tightly packed tentacles and also a fascination with the long sweepers they are reputed to send out. So, found a nice one, and he has moved in. It is placed in a spot where the sweepers will not be able to touch any other coral, so that should not be a problem.

Resident of the Month

Dear Marther ReefKeeper

Dear Marther,

A container of water that is left in the open air will soon disappear as the water turns into water vapour and is carried away in the air, i.e. it evaporates. And since the only thing that leaves the container is the water, then gradually the concentration of any compounds contained will increase. If a container of saltwater is left out with a given salinity, and this same process occurs, then the salinity will rise. For marine animals, which are use to a particular salinity, this rise will cause health problems and even death. How do I overcome this problem with a reef aquarium?

From,
Evap Oration

Dear Evap,

This process is a part of the reason for the high level of dissolved compounds found in the ocean such as sodium (Na⁺) and chloride (Cl^-). As water runs over land it dissolves almost anything that it comes into contact with, such as metals, minerals etc. This is carried to the ocean along with the water. In the ocean the water is being continually evaporated to become rain that will fall on land, carrying more dissolved compounds to the ocean and concentrating the dissolved species. If this process is spread over several millions of years, then a substantial concentration can be achieved as such found in the oceans currently. This process is also dramatically shown by salt lakes, where it has gone to the extreme. Anyway, I diverge, back to your question.

The water from a reef aquarium that is lost as evaporation has to be replaced. Not only that, but you also have to put back what is actually lost, pure water. If water that has some dissolved compounds in it is used then this will accumulate, in much the same way as it is concentrated in the ocean as indicated above. Therefore the water has to be purified in some way preferably. This is usually down via distillation, reverse osmosis, or deionisation. Some places have tap water that is good enough to use, but it is much better if you purify it.

Now that you have what to put back into the system, how do you actually put it in? There are actually quite a few techniques, with each one having its advantages and disadvantages. Which one that is used depends on the system and available equipment.

1. Manual Refill. Have a mark on the side of the tank, and when the level drops below it add more water. This is the simplest technique, but can be very erratic. It relies on you checking the height regularly and then adding the water. If it is left too long, or too much is added, then wide swings in the salinity can result.
2. Float Valve. A float valve with a float attached is put into the system and the ball/valve string adjusted to the water height required. It is connected to a reservoir of water at an elevated height. As the water level falls, the float will fall until it opens the float valve. Water flows in, increasing the water height, which will then shut the valve. This is what I think is the best way to do it, very cheap, simply to do, a minimum of moving parts, and does not require any power to operate.
3. Continuous Drip. Water is continuously dripped into the tank at a rate that has to be determine. Usually an IV bag can be used for this, but can also build something using air line or something like that. This is the best way to maintain the salinity in very small systems, as there is usually no space for valves or switchs. Also a significant height change, which is required for many of the others, can actually be a large salinity change in such a small tank.
4. Dosing Pump. A dosing pump can be connected up in three different ways, continuous operation, intermittant operation on a time, or connected via a float switch. With the continuous operation, the correct rate has to be determine to match the evaporation rate, much the same as the continuous drip method. If the pumping rate of the dosing pump is too large, then this can be counteracted by having the pump on a timer, coming on several times a day to add the water. The third way to have it connected up is via a float switch. The switch monitors the level, and when it falls to a certain level the dosing pump is activated. A little more complicated than the others, but still works well. Although there are more things to go wrong, and a pump is used.
5. Float Valve/Dosing Pump Direct To Water Supply. This just used two of the above, but instead of being connected to a water reservoir, it is connected directly via a filtration system to the mains water supply. This is very handy, as the water reservoir does not have to be periodically refilled. The bad news is, if the valve or swith fails then you get a flushed tank, a large wet patch on the floor, and a tank full of dead animals.
6. 'Water Dispenser'. As the name implies, this is based on the technique used in water dispensers, the ones with a large, inverted plastic container and go blurp every now and then as water is drawn from them. A rigid, air tight reservoir is suspended above the tank, with the outlet suspended to the water level required. The outlet must be wide enough to allow air to move back up it with the water in there, so more than 2cm is a good idea. As the water level drops, then air flows up the outlet pipe, into the reservoir and thus letting water flow out. It continues to flow out, with the blurping action, until the correct level is attained such that air cannot flow in again. A very in genius technique, but the reservoir has to be rigid.

Note that most of the above listed techniques require a spot in the system where the water height is monitored. To ensure that the salinity is kept as constant as possible, then you want it such that a small total volume change in the system causes a large height change in one particular spot. This can be difficult if you rely on the height change in the main display tank, which has a large volume and a small volume change is barely discernable as a height change. The best way to achieve this is to have a weir arrangement somewhere in the system, such as the sump. Water is fed to one side, this fills up, then water flows over the top. On the otherside a pump returns the water to the main display tank. If any water is lost from the system, then it will go 'missing' from the pump side of the weir. Also the narrower the compartment, i.e. the larger height change there is for a given volume loss, then the more accurate the system salinity can be maintained. In this compartment is where a float valve/switch etc. is typically mounted.

A little word of advice for when ever you are planning to add something to your reef system, a few questions that you should ask yourself first.

• What will happen if something goes wrong?
• What will happen if it fails?
• Are the consequences dangerous with a safety risk to yourself/your tank/your animals?
• Will it cause major damage to the system/surrounds or just make a big mess?
• Are you willing to take any of those risks with your our health, that of your animials, or surrounding property?

From,
Marther ReefKeeper

Special Feature

Sorry, none this month, but there is some in the pipeline. But you might be interested in having a look at the Residents Directory, this has been updated. About 6 or more residents have been added, and information is quite a few others has been changed or added too.

You Wouldn't Believe It!

..... all colonial corals are communists! The stomach cavities of colonial polyps are interconnected enabling food to be shared among all the polyps within the colony. So if one polyp catches more than its fair share of food, it is shared between the other polyps in the colony.

..... the Box Jellyfish, a jellyfish found in Northern Australia waters, has tentacles that each contain up to 750,000 stinging cells, nematocysts. These are used to paralyse its prey before eating. The tentacles are used to hunt, being raised and lowered allowing 'fishing' at various depths.

Bereavement Notices

None
Another good month, though a couple of the Acropora sp. are looking a little on the sick side. I think this may be due to a low and fluctuating calcium level in the water, which is a result of somethings that have been occuring with the calcium reactor. Well, this is what I think it is, as I can not find any other reason, everything else is fine.

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