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Reeftank Log 11/99

Saturday, November 27, 1999

I went to the November 20th meeting of SEAbay, Saltwater Enthusiasts Association of the San Francisco Bay Area, in order to attend a presentation by Steve Tyree on SPS corals and the use of living sponges as filters. I learned quite a few interesting facts, purchased two SPS corals (an Acropora formosa and a Stylophora pistillata), and a sponge rock, and even won a 20-gallon long acrylic TruVu tank in a raffle. Steve made some interesting observations about SPS corals that will affect how I maintain not only SPS corals but also other specimens in my reeftank.

Concerning water flow, Steve mentioned that the current coming directly out of most powerheads (exceptions are the 100 gph or smaller powerheads), when directly pointed at an SPS coral, is too much current. He's hoping powerhead manufacturers will develop powerheads with a wider outlet to disperse the current. Presently, I have two Maxi-Jet MP900 powerheads at opposite ends of my 50-gallon tank attached to a Red Sea Wavemaster wavemaker. The current from the powerheads is directed slightly upwards so that the current is dispersed by hitting the surface of the water and pouring back downwards and across the tank. This method of dispersing the current of the powerheads appears to be working fine for the Xenia at the top of the tank. Hopefully, this method of dispersing the current will also be beneficial for the SPS corals I bought from Steve.

Lighting was the next subject that Steve covered. He has had positive experiences with metal halide lighting. Recently, he has been using 10K and 20K lighting which he feels provides more of the short wave spectrum that shallow water SPS corals can utilize for photosynthesis. He noted that over time, the wavelength of a bulb shifts toward the red end of the spectrum and also loses its overall intensity. With a new bulb, it would be prudent to carefully watch how "powerful" it is by noting the reactions of the corals in the tank. Strict dictums on how many hours to light one's tank don't work when the characteristics of a bulb change over time. With a new bulb, he has kept the photoperiod to only 4 hours. Toward the end of a bulb's lifecycle, he may keep the bulb on for 12+ hours. He told a cautionary story of how a public aquarium changed the bulbs over a stony coral exhibit, but didn't adjust the photoperiod accordingly. The result was a lot of lost corals and coral growth. Luckily, the aquarium was able to realize their error and the whole exhibit wasn't destroyed. Steve didn't have any experience with power compact lighting, but the two SPS corals I purchased from him seem to be doing fine after a week. I just hope they color up well.

Regarding the need to provide very bright lighting for SPS corals, Steve made two other interesting points. In studies on the photosynthetic needs of SPS corals, it turns out that more light than is necessary is just a waste of electricity. It turns out that after a certain amount of intense light, the zooxanthellae in SPS corals just shut down. Any extra light doesn't contribute to the photosynthesis or growth of the zooxanthellae and coral. Of course, Steve is talking about the intense light found in areas like the Great Barrier Reef. Still, I think there are people out there who are probably wasting electricity and generating extra heat by using more light than is necessary for their SPS corals.

The other interesting point was that most of the SPS corals collected for the hobby are only collected from shallow waters, 20 feet or less, because it's much easier to collect from a shallow depth. There are two problems with this. One, since these corals are adapted to high levels of light, a reef aquarist must provide high levels of light for the SPS corals' survival. Two, since these corals may only display their bright, non-zooxanthellae pigments under very powerful light, even if a reef aquarist is able to maintain a specific SPS coral, it may only be a dull brown color under artificial lighting. There are a greater diversity of SPS corals within the zone from 50 to 20 feet, but they are much harder to obtain. If they could be collected for the reef aquarium, we may find SPS corals that will thrive and maintain their bright colors under lower light levels.

Steve told me that the Acropora formosa will display blue tips under strong light and the whole body will turn blue under very strong light. I've put the frag I purchased from him only a few inches from the water's surface. I hope the 2x110 watt power compacts I have directly above the frag produce at least blue tips. Presently, the body of the coral has turned a darker brown and the very tip of the frag is blue.

The Stylophora pistillata is a frontier coral that should be easier to maintain than the Acropora. It's polyp extension gives it a bushy appearance. I hope its pink color becomes more intense.

Steve made some cursory remarks concerning maintaining calcium and strontium levels for SPS corals, but the focus of his talk was on the importance of the correct lighting and water flow.

Steve wrapped up by discussing some new research he was doing on living sponge filters. Since I already have glass sponges living in my sump, I decided to purchase a pink sponge rock from him. I'll soon have two Cercona Cell-Pore rocks 4"-6" in diameter in the sump to provide more colonization surfaces for sponges and other filtering organisms.

In order to provide more room for the Cell_Pore rocks, I've moved the two powerheads that are used to such excess air out of the overflows so that they flow into the larger sump area of the sump. This circulates the water in the larger sump area in a more effective way for heating and additive purposes. It also makes it easier to attach the airline tube that goes into the venturi port of the powerheads.

Polyp extension on the SPS corals in the tank is looking very good.

I've noticed quite a few baby peppermint shrimp in the refugium hiding underneath the rocks. They're definitely getting bigger. I hope I'm able to raise them up to full size. Color in the Entamacea quadricolor and the Goniopora in the refugium has been coming back.

Sunday, November 28, 1999
I made my own aragocrete rocks and plugs today. The rocks are somewhat chunky and ugly, but they're my first start. I'll probably use the ones I made today as base rock in a future tank. I used a metal mini muffin pan for the plugs since I couldn't find any plastic egg containers. I hope the plugs separate well from the pan. I left everything outside so the concrete will take a bit longer to set. I hope I made the concrete the right consistency so that it doesn't fall apart.

Monday, November 29, 1999
Aragocrete rocks and plugs were hard to the touch by this evening. The rocks have flat surfaces where I merely poured the concrete mix on to the aragonite they look pretty artificial. I'll just hide them in the back and use PVC to support them for the reef aqarium I use them in. I'll have to dig depressions in a deeper bed of aragonite and pour the concrete mix into the bed next time so that I get more natural looking rock. I was excited that I was able to tap the bottom of the muffin pan with a hammer and knock the aragocrete plugs out in one piece. I initially tried to tap the plugs out with a rubber mallet, but the mallet didn't have the concentrated force needed to knock out the plugs. I placed the plugs in a plastic pail and filled it with four gallons of water. I'll change the water twice a week and see how well that cures the plugs. GARF sent their order of mixed corals out today. I look forward to seeing what specimens they sent out to me.

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