Reef Tank: Coral En Route

This morning I placed an order at Live Aquaria for a stony coral frag pack. While stony corals can be more difficult to keep because of their increased need for light, calcium, and water current, I find them some of the more interesting species and was what I always envisioned keeping in my tank. The package I ordered is for five frags (small fragments from a larger colony) of aquacultured coral colonies. Aquacultured specimens, as opposed to wild card, are purportedly more tolerant of aquarium conditions and less likely to be severely traumatized by the introduction to a new tank.

My new metal halide fixture arrives tonight as well, so I hope to be able to get that setup and post pictures of the tank. This should represent the last piece of equipment that was part of my original tank plan, although I've already thought of several things I'd like to change and upgrade in light of the decision to keep stony corals primarily.

Parameters from Last Night:
Temp: 80F
SG: 1.025
pH: 8.3
Ammonia: 0
Nitrite: 0
Nitrate: 20ppm
dKH: 9
Calcium: 400ppm
Phosphate: 0

Reef Tank: More Testing

Here is a graph I generated showing the process of the nitrogen cycle in my tank to date. Note that the x axis is not to any particular scale as I don't test at regular intervals. Still, it shows all tests going in the right direction, towards 0.



Today I got another set of tests for the reef aquarium. Once corals have been added to the tank, it is important to keep levels of calcium high in the water so that they can create their skeletons. It is also important to keep the carbonate hardness of the water level (also known as alkalinity) high to make this calcium accessible to the corals and buffer against pH swings. The third test measures phosphates, which form from animal waste and precipitate calcium, making it unavailable to be used. Phosphates can also serve as fertilizer for algae growth. To summarize, I am looking for calcium levels between 400 and 500ppm, KH at 140 to 215ppm, and no signs of phosphate.

Todays Parameters:
Temperature: 81F
Specific Gravity: 1.026
pH: 8.0
Ammonia: 0ppm
Nitrite: 0ppm
Nitrate: 20ppm
Phosphate: 0ppm
Calcium: 480ppm
KH: 179ppm

I must say I'm surprised at how well everything has gone so far. The water levels above, aside from a slightly low pH, could probably sustain coral growth quite well. With ammonia and nitrite undetectable, the tank is ready to be populated. I am going to hold off at least another week before stocking, while I finalize the list of corals and fish I want to keep in my tank. I also need to upgrade my lighting fixture to metal halide before I can order any coral. Another week or two with the snails and hermits should help the tank to slowly prepare itself for these additions.

Reef Tank: Snails and Hermits

On Saturday morning I did another round of tests and found ammonia to have dropped to zero. Nitrites were still low and nitrates were elevated to 40ppm. I decided to try and add some of the first inhabitants to my aquarium, a group of snails and hermit crabs who could feast on the new growth of diatoms and the stuff that came in on the live rock.

I went to Skipton's Pet Center in Boston, which is the best fish store in metro Boston, as far as I know. They helped me settle on a dozen Nerite snails and ten hermit crabs, a few different varieties of Clibanarius, including red and blue colorations. Both snails and hermits originate in the Caribbean and are quite common, which makes them affordable to purchase compared to other species. The snails are intertidal and therefore spend a lot of time crawling above the waterline to breathe. Everyone appears to have survived their first night, and I've been watching both snails and crabs tear into the diatoms on the rock and glass.

Still trying to figure out the white balance while shooting under actinic light, so please excuse the yellow tone of these photos. The picture of the blue hermit crab is closer to the correct coloration. Also, if you go to a larger view of the snail photo, you can see the barnacles on its shell extending their feeders. Pretty cool!







Saturday Parameters:
Temperature: 81F
Specific Gravity: 1.026
pH: 7.9
Ammonia: 0ppm
Nitrite: 3ppm
Nitrate: 40ppm

Reef Tank: Diatoms

Last night I noticed a golden-brown colored dust growing on the substrate and rocks. I spent some time searching for algae species identification charts, and eventually came across an About.com article regarding diatoms. A trip to Wikipedia and some other resources confirmed that was what I had most likely observed in my tank. Of particular interest to me was this section from About:

This type of algae outbreak typically occurs when a tank is just completing or has finished the nitrogen cycling process, new live rock is introduced, as the curing process can add nutrients when some organisms on the rock dies off, or tank maintenance has been neglected.

Obviously that would pertain to current events in my reef tank. I had assumed that ammonia levels, which had been as high as 8ppm three days earlier, would require at least another week to subside, and had resolved not to waste my time and test kits checking it every day. The growth of diatoms and subsequent information about them forced a change of mind, and I conducted my usual tests this evening with surprising results: ammonia had indeed dropped to somewhere between 0.25 and 0ppm, an impressive down swing from the levels recorded on Sunday. Nitrite and Nitrate were still high, but that would be expected as they are the products of processed ammonia.

Also of interest was this summary of diatoms and their use of silicates, found in the Wikipedia article:

Diatoms cells are contained within a unique silicate (silicic acid) cell wall comprised of two separate valves (or shells). The biogenic silica that the cell wall is composed of is synthesised intracellularly by the polymerisation of silicic acid monomers. This material is then extruded to the cell exterior and added to the wall. Diatom cell walls are also called frustules or tests, and their two valves typically overlap one other like the two halves of a petri dish. In most species, when a diatom divides to produce two daughter cells, each cell keeps one of the two valves and grows a smaller valve within it. As a result, after each division cycle the average size of diatom cells in the population gets smaller. Once such cells reach a certain minimum size, rather than simply divide vegetatively, they reverse this decline by forming an auxospore. This expands in size to give rise to a much larger cell, which then returns to size-diminishing divisions. Auxospore production is almost always linked to meiosis and sexual reproduction.

Once again, an insightful article from Randy Holmes-Farley helps to clarify both the cause and effect. As mentioned above, diatoms construct their cell wall from silicate, hence their presence could be considered an indicator of silicates being present in the aquarium. His article discusses how silica occurs in the ocean and in the aquarium, as well as what organisms use it and how it can be controlled and dosed. Great stuff.

My assumption is that there would be a high level of silicates found in my tank due to a number of recent inputs:
• Unfiltered tap water for the initial tank fill
• Sand and sediment on the live rock
• Live sand substrate

So there should be plenty of raw material for diatoms, in addition to the high levels of light for photosynthesis (I've been running the tank lights 8 hours a day) and nitrate for fertilizer. Conventional wisdom seems to indicate that after the initial outbreak of diatoms in a new aquarium one can expect green algae to replace it. My initial hobbyist panic response to seeing my pristine new white sand bed polluted with some form of new algae has since been replaced with curiosity now that I've learned about the circumstances under which it appears. I intend to see if I can get a sample out of the tank and take a look under the microscope this evening, as the imagery on Wikipedia is quite stunning.

Todays Parameters:
Temperature: 81F
Specific Gravity: 1.026
pH: 7.9
Ammonia: .025ppm*
Nitrite: 5ppm
Nitrate: 10ppm

* The color of the ammonia test was actually somewhere between 0.25ppm and 0ppm, and closer to 0. In the interest of caution I am rounding up on the chart.

Links from this post:
Randy's article in Advanced Aquarist about silica and diatoms:
http://www.advancedaquarist.com/issues/jan2003/feature.htm

Wikipedia article on diatoms:
http://en.wikipedia.org/wiki/Diatoms

About.com article on diatoms:
http://saltaquarium.about.com/cs/algaecontrol/a/aa091100.htm

Chemistry: The Nitrogen Cycle

As mentioned previously, my reef tank is currently going through a startup phase in which the nitrogen cycle becomes established. As there isn't much for me to do until this phase completes itself, I decided to dig a little deeper on the chemistry of this cycle and how it specifically relates to reef aquaria.

Fortunately for those of us who spent too much time goofing around in high school chemistry, there are a number of talented professionals contributing to the knowledge base. Of particular note is Randy Holmes-Farley, a chemist at Genzyme (which just so happens to be down the street from where I work). He writes articles for several online reef aquaria journals, and this morning I enjoyed reading two on the nitrogen cycle: Nitrite and the Reef Aquarium and Nitrate in the Reef Aquarium.

Of specific interest in these articles were a few points that differ in marine aquaria from freshwater systems, and that also defy what is passed along in forums as conventional wisdom. For one thing, it appears that in saltwater systems nitrites are not considered highly toxic unlike in freshwater tanks where they are considered as deadly as ammonia. Randy also lists out proven methods of eliminating nitrates in the reef tank, which though also not considered highly toxic, can be contributors to nuisance algae. Both articles are a great read for those looking to get an introduction to these steps in the nitrogen cycle.

Reef Tank: The Cycle Begins

Once live rock has been introduced into a new aquarium the waiting game begins. Live rock brings with it life of all forms, from simple bacteria and algae cells up to more advanced life forms like sponges, worms and even coral polyps. Naturally on the long journey from the South Pacific (specifically, Tonga) much of this life perished. The combination of live and dead organisms helps to jump start the nitrogen cycle. Reef Central has a good FAQ regarding the nitrogen cycle as it pertains to reef aquariums.

In short, dead organisms arriving on the live rock decay, creating ammonia which is toxic to all life and probably killing off other organisms that had managed to survive the trip. Fortunately bacteria present in the rock are capable of converting ammonia to nitrite (still toxic to marine life) and then converting it further to nitrate (somewhat toxic at higher levels, but not as bad as the other two). As the patient new aquarist, I must sit back and watch this cycle slowly take place over the next two to six weeks, watching via test kits as the levels of ammonia, nitrite and nitrate change in the aquarium. Once the bacteria has taken hold ammonia and nitrite levels should read at 0 ppm. Nitrate may still show up in minute levels and can be minimized via water changes.

I plan on testing the parameters every four days or so to monitor this cycle, and to perform 20% water changes once a week to further reduce toxins. As a sign of a successful cycle beginning, we're looking for a drop in ammonia and a rise in nitrate to indicate the bacteria are at work. The protein skimmer has been pulling out some very light skinmate but doesn't appear to be quite as dialed in as I would like. I'm not sure if this is related to a lack of nutrients in the water to be skimmed or some other variable.

Todays Parameters:
Specific Gravity: 1.0255
pH: 7.9
Ammonia: 8ppm
Nitrite: 5ppm
Nitrate: 10ppm