I live in Hong Kong and have been keeping marine aquarium fish since I was a child. In 1996, I started a 120 gallon (48″x24″x24″) marine fish tank. The aquarium is a standard 4 foot tank with a custom made wooden cabinet for support. There were neither holes drilled nor overflow included. About 3 years ago, I went to visit the Waikiki aquarium in Hawaii. I was deeply impressed by the beauty of the reef tanks here. That started me reading magazines, books, and surfing the internet where I obtained valuable information about reefkeeping from advanced aquarists such as Terry Siegel, Randy Donowitz, Doug Robbins, Craig Bingman, etc. The tank of Gregory Schiemer (seen in Eric Borneman’s book) and the tank of Terry Siegel (seen in aquarium fish magazines) inspired me a lot. Three years ago, I changed my fish only tank to my first reef tank, where there was an excessive outbreak of annoying algae. Soon after, I reworked the design and connected a mud refugium (24″x20″x20″) to the main tank.
Philosophy / Methodology
My aim was to construct a community tank (with a heavy bioload) dominated with stony corals. I tried to experiment with high nutrient inputs and outputs. I use high intensity lights and heavy feeding for energy input. On the other hand, heavy protein skimming and periodical harvesting of macroalgae act as nutrient output. Besides that, I used a 3 to 4 inch deep live sand bed, lots of live rock, which are assisted by a well established mud tank for biological filtration. These methodologies have been working well in my tank for the past two years.
Water Circulation
I use 3 tunze plus 1 Taiwan powerheads to provide random currents throughout the tank. All of the powerheads are controlled by timers. All three tunze powerheads provide pulsating current. I also employ a Seaswirl oscillator connected to an Iwaki MD-30 to provide turbulence. Furthermore, I built and use a Bruce Carlson Surge Device which is placed on top of the tank. Every few minutes, a huge amount of water is poured downward from the reservoir container above the tank. The water level of my tank rises up and down periodically due to the surge device. The water current is ample throughout the tank.
Lighting
On my visit to the Waikiki aquarium, I found that they use natural sunlight, supplemented by metal halides. Inspired by the tank in Waikiki, I use very intense lighting over my SPS corals, certainly beyond the common recommendation of North America aquarists. Lighting is provided by 6 metal halide bulbs: One 1000 watt 10,000k (BLV) bulb, two 400 watt 20,000k (Radium) bulbs placed directly above the tank. Three 250-walts with 10,000k (BLV) bulbs are angled towards the water surface. The photo period for all metal halides is12-hours, except that the 1000-walt halides are only on 5 to 6 hours everyday. The bulbs are renewed every 9 months. Therefore, my tank is extensively illuminated, requiring a certain period of time for my coral to adapt this lighting scheme. The photo period is reduced accordingly after I change bulbs. Lighting over the mud refugium is supply by a 150-watt AB metal halide light which is switched on when the other bulbs are off over the display tank.
Filtration
Because I try to keep a lot of fish (more bioload) in the tank three protein skimmers serve as my primary filtration system — One H&S skimmer, one AB skimmer, and one DIY 5 foot air driven skimmer. There is no mechanical filtration of any kind. Activated carbon is used about once every two months. Macroalgae is harvested from the mud tank periodically. The 3 to 4 inch live sand bed of my tank and the invertebrates serve the purpose of biological filtration.
Calcium and additives
A H&S kalkwasser reactor is used to keep dKH at 8-9. All the evaporated water of the tank is automatically replaced by a calcium hydroxide solution from a DIY calcium reactor during night time. Calcium hydroxide powder is mixed with DI water inside the reactor with a magnetic spinner underneath to produce a good quality calcium hydroxide solution, and a solution of strontium chloride is added biweekly.
Current Inhabitants
Seventeen fish are kept in my tank. My fish population includes a yellow tang ( Zebrasoma flavescens ),5 blue tangs ( Paracanthurus hepatus ), a yellow tail demoiselle ( Chrysiptera parasema ), a foxface rabbitfish ( Siganus vulpinus ), a clownfish( Amphiprion nigripes ), 5 Bartlett’s anthias ( Pseudanthias bartlettorum ), and 3 Evan’s anthias ( Pseudanthias evansi ).
Corals
There are many colonies of SPS corals such as Acropora, Pocillopora, Montipora, Seriatopora, plus soft corals such as Xenia, Anthelia, photosynthetic gorgonians, etc.
Clams
There are two 15 inch T. derasa and three 3 inch T. squamosa
Other invertebrates
I have a large population of blue legged hermit crabs ( Clibarius tricolor ), one sea cucumber and many algae eating snails of genus Turbo, Nassarius species, etc. Also, there are numerous worms, pods, amphipods and mysids present in or on top of the sandbed.
Feeding Regimen
I try to heavily feed my tank. I feed a variety of foods. Huge amounts of Artemia nauplii and DT phytoplankton are fed daily. Live rotifers are fed twice a week. All the Artemia nauplii and rotifers are cultivated and enriched by Selcon or Zoecon. Nori is regularly fed to the fish as well.
Maintenance Regimen
I perform 5% water change biweekly. I clean the front glass twice a weekly and clean the skimmer as frequently as possible. Macroalgae is harvested regularly from the mud tank.
Chemistry
The pH is around 8.3, alkalinity 8-9 dKH, calcium ~420ppm, S.G 1.025-1.027, Nitrate and Phosphate are present at low levels and haven’t been checked for long time. Temperature is kept between 79F-84F. I use two powerful chillers to control the temperature because the temperature in Hong Kong is very hot in summer.
Special feature of my tank
My 15 inch T. derasas have been kept for more than 2 years. They regularly emit sperm into the water column but they never emit eggs. I guess that they are not mature enough. The barnacles and other invertebrate spawn regularly (the water of the tank will turn milky during the spawning event). The biodiversity of my tank is great. Different types of sponges are visible everywhere. Many copepods, amphipods and mysids can be found underneath the live rock. Bristleworms are found all over the sand bed.
Problem encounters
Nearly 90% of corals in Hong Kong are imported from Indonesia. All of them are wild caught colonies. I encountered an RTN situation after I introduced a wild SPS colony in to my tank. I also developed a Valonia problem due to excessive feeding. Aiptasia may become a problem for me in the future. I have observed that they sting at the base of some Acropora colonies. I am still at the starting point of my road toward advanced reefkeeping. Many things still need improvement, but I am willing to learn from my mistakes.
Chung Wing Hung can be reached by email at [email protected]