Building a Reef Aquarium Part 2

In my last article I covered the initial installation and plumbing of a 600 litre aquarium, in this article I will be covering some of the main pieces of equipment used to maintain water chemistry and the environment.

The Test Run
After finishing all the plumbing work between the main tank and the sump it was time for a test run to make sure that there were no leaks and that all the plumbing was sound. The tank was filled with ordinary tap water and the main circulatory pump turned on. It is worth while checking each and every piping joint at this point as it is more troublesome to go back and fix a problem later, fortunately all the joints were sound, the tank was perfectly level and the water levels were running exactly where I wanted them. There was one issue in that the noise from the drainage pipe to the sump was louder than I would like it so I will be making some changes to the drainage plumbing to try to reduce the noise of the water flowing into the sump. Now that I had finished the first test run the tank was drained and it was time to install some of the main pieces of equipment.

Protein Skimming
This system is being run with the Berlin style filtration method, that is live rock and protein skimming. Protein skimming is an essential part of this type of system. Otherwise know as foam fractionation the process works as protein molecules are attracted to the surface of the water, or in the case of a protein skimmer the surface of the bubbles. The bubbles rise up the main contact chamber and a foam is produced and collected in a collection chamber. The objective of the skimmer is to remove organic waste products from the water before they are broken down by bacteria and end up as nitrate. The effectiveness of a skimmer depends largely on the size of the contact chamber, the volume and size of the bubbles injected into the contact chamber and the contact time between the bubbles and the water before the bubbles reach the surface.
There are numerous different makes of protein skimmer on the market, air driven skimmers, counter current skimmers, pin wheel skimmers and venturi skimmers, some of them are very effective, some are almost a complete waste of money. You will also find that some protein skimmers on the market are extortionately priced, so shop carefully before you buy. I settled on one of the new range of V2 skimmers from Tropical Marine Centre, the V2 Skim 1200. I chose this make of skimmer for a number of reasons, they are well made and thought has been put into the little design details that make them easier to use. The collection cup is fitted with an easy to remove connection and the water level adjustment dial makes the controlling of the skimmer very easy. The reaction chamber of this unit is large and the venturi injector supplies a good amount of micro bubbles into the unit, I have also run one of the smaller V2 skimmers on another system so already knew that they work well. One of the biggest factors however is that these skimmers are very economically priced. The V2 1200 is marketed for aquariums up to 1200 litres so it is oversized for this aquarium but it does not hurt to have the capacity there should you decide you need it or want to heavily stock your aquarium with inhabitants. With a retail price of £179.99 I think these are one of the best value for money skimmers on the market.

The skimmer was installed in the third section of the sump along with the pump that drives it and positioned so that the collection cup is easily accessible. This can be seen in Figure 1.

The Top Up System
In any system water is going to be lost through evaporation, in a marine system this means that as pure water is evaporated the salinity of the remaining water is going to increase. An increase or fluctuations in salinity is obviously stressful to our aquarium inhabitants and so it is essential to replace the water lost through evaporation as it happens.

The easiest and most effective way of doing this is through an automatic top up system. This incorporates a float switch that controls a pump linked to a reservoir of reverse osmosis water. It is paramount that only RO water is used in reef systems as untreated tap water contains far too many contaminants. The float switch is placed in the sump where the water level will drop as evaporation occurs. As the water level drops the float switch turns on the pump that will automatically dose RO water into the sump to replace that lost by evaporation. There are a number of float switches on the market to choose from, I selected the D &D float switch with mains adaptor. Although I think these units are rather expensive for what they are I have used them for many years and have never had any problems with them sticking or failing. This particular model is connected to a mains adaptor that any pump can be plugged into. The float switch can be seen in the sump in figure 2.

For dosing the RO water into the sump I am using a peristaltic pump that has a flow rate of 15ml per minute. Further down the line I will probably install a Kalkwasser stirrer into the system, water will then be drawn from the RO reservoir and fed through the Kalkwasser stirrer before it is dripped into the sump. When using Kalkwasser in conjunction with your top up system it is possible to connect the float switch to a timer so that it only comes on and tops up the system at night. The high pH of the Kalkwasser water helps to counteract the drop in pH that occurs in aquariums at night due to the changing balance of photosynthesis and respiration.

Cooling and ventilation is very important for a reef system. The water of coral reefs generally fluctuates between 23 and 28 C over the period of a year, although in the regions that make up the limits of where coral reefs can be found temperature fluctuations of up to 20C can occur over the year. It is known that temperatures between 23 and 27C are most favourable for corals, however if corals are exposed to temperatures that exceed 29-30C for extended periods of time (greater than 24 hours) then the consequences for the corals can be fatal. In a reef system we should try to maintain the water temperature between 25C and 27C over the period of a year, you should certainly strive not to let the water temperature exceed 28C or drop below 24C.
This system will not be incorporating a chiller, I have had smaller reef systems in this room before and with the surface to volume ratio of the aquarium and the lighting that I am using I know that I do not need one. Over the summer months it will be helpful to install a small fan blowing across the surface of the tank water to help reduce the heat from the lights and increase the cooling effect of evaporation but for now it is not necessary.

One thing that is necessary though is good ventilation in the cabinet. A build up of condensation will cause all sorts of problems for the cabinet itself even with the sealed joints that it has. Good ventilation through the cabinet will also help to reduce the temperature around the sump in the summertime. To help ventilate the cabinet which already has large windows cut out of the back I installed a small extractor fan in one of the windows. Thick polystyrene was cut and fitted into one of the ventilation windows and a small axial fan installed in the middle to draw air out of the cabinet. This can be seen in figure 3. This fan will run 24 hours a day to prevent condensation build-up in the cabinet.

Calcium Reactor
The maintenance of calcium and carbonate hardness levels in a reef aquarium is only one of the factors of water quality but it is an important one and if you are running a system that is to be dominated by hard corals then a calcium reactor is an essential piece of equipment.

The calcium concentration of natural reef water is around 420ppm and the carbonate hardness is around 8dKH. To ensure that calcium and carbonate levels are not a limiting factor in the growth of corals I like to run my systems at 420-440ppm calcium and 8-10dKH. You will find that the dKH levels of the aquarium water may drop faster than the calcium levels, in fact in a heavily populated SPS system the dKH levels of the water can drop by 2 points a day unless continually buffered.

A calcium reactor works by adding both calcium and carbonate to your system. A reaction chamber contains calcium carbonate media that will dissolve at a low pH releasing calcium into the water and raising the dKH level. Water is slowly pumped from your aquarium, through the reaction chamber and then back into your aquarium. Carbon dioxide gas is injected into the reaction chamber which dissolves in water forming carbonic acid which causes the pH of the water to drop enabling the calcium reactor media to dissolve. Maintaining the correct dosing rates through a calcium reactor and the correct levels of calcium and carbonate in your aquarium requires a fair amount of water testing and regulation of the reactor. This can be done manually or you can use electronic equipment to do some of the job for you.

Most of the calcium reactors and particularly the monitoring equipment that is on the market is fairly expensive but TMC have just brought out a range of new calcium reactors and monitoring equipment that are very economically priced so I decided to go for the whole shebang  and test out this new equipment.

Firstly the calcium reactor itself. I opted for the V2 React 1000 which is rated for aquariums up to 1,000 litres and holds up to 3kg of media. I would not want a reactor that holds any less media than this for a heavily populated SPS system of the size I was building or else I would have to keep replacing the media as it dissolves too frequently and for me the less maintenance the better! This calcium reactor has lots of great little features that most other calcium reactors do not. Firstly it has an automatic water intake system where water is drawn from your sump without the need for a second pump or feed from your main return pump. Usually to supply the water into a calcium reactor I will take a feed off of my main return pump and into the reactor. The flow rate through your calcium reactor is important and it is essential to be able to keep this flow rate constant and adjustable as the demands of your aquarium change as your corals grow. With the V2 calcium reactor the main recirculatory pump also draws water from your sump via a thin flexible hose that is controllable with a small valve. The idea looks good and time will tell if this system provides a reliable flow rate through the reactor. I will report back on this when the reactor is up and running. The rest of the reactor is well made with a large, easy to open top for replacing media that also incorporates a pH probe holder. There is the usual bubble counter but also a drip counter so you can easily see the flow rate of water through the reactor. Not only this but the range of reactors come supplied with a CO2 pressure regulator which you would normally need to buy separately and with a price tag of £159.99 it is a very economical unit.

The reactor has been installed in the cabinet next to the sump and can be seen in figure 4. You will notice that I have added a second chamber that is hanging on the side of the sump, this is to help raise the pH of the water going back into the sump. For the calcium reactor to work the carbon dioxide that is injected into the reactor has to cause the water to drop to a pH of around 6.5 to enable the media to dissolve, as this water flows back into your aquarium it can depress the overall pH of your aquarium water. To help avoid this the water is passed through this second chamber which contains more media, as the media dissolves it helps neutralise the carbonic acid and raises the pH of the water before it flows back into your aquarium.

As I mentioned the water in the reactor needs to be at a pH of around 6.5 and this is achieved by the addition of carbon dioxide gas which forms carbonic acid in water. The amount of carbon dioxide gas that is used needs to be carefully regulated and the amount needed is determined largely by the flow rate of water through the reactor. The higher the flow rate of water through the reactor the more carbon dioxide needs to be used to keep the Ph at 6.5. The water flow rate through the reactor should be determined by your aquariums demands, the more calcium and carbonate that gets used up in your aquarium the greater a flow rate you will need.
You can monitor that the reactor is working properly by measuring the dKH of the effluent leaving the reactor, this should be at around 30-40dKH, and by measuring the calcium and carbonate levels in your aquarium you can see if you need to turn the water flow rate and hence carbon dioxide flow rate up or down. However for a more reliable system than regularly testing the water yourself you can use electronic monitoring and controlling systems and this brings me on to my next new bit of kit the V2 pH Controller/Monitor. I actually saw these advertised on the back of Ultramarine magazine and they are brand new to the market. The controllers work by using pH probes that continually monitor the pH of the water in your calcium reactor, the pH probe is inserted through the top of the calcium reactor and this can be seen in the top of the picture in figure 4. The controllers are then linked up to a solenoid valve which controls the flow of carbon dioxide to your reactor (shown in figure 5). By setting the required pH on the controller (i.e. 6.5) the water is monitored and if the pH climbs above 6.5 then the controller switches on the solenoid valve and allows carbon dioxide to be dosed to the reactor, if the pH in the reactor drops bellow 6.5 then the controller switches off the solenoid valve and stops the dosing of carbon dioxide. In this way the pH of the water in the calcium reactor is maintained at a constant level of 6.5. All you need to do is to measure the calcium and carbonate levels in your aquarium water and increase or decrease the flow rate of water running through the reactor and the controller will automatically adjust the carbon dioxide dosing as necessary. This model of controller/monitor (shown in figure 6) also comes with a pH monitor for your main aquarium. A second pH probe is placed directly in your aquarium and constantly monitors the pH of your aquarium water and displays the information on a large LED display.

This type of unit will make the controlling and monitoring of the calcium, carbonate and pH levels of the aquarium water far easier than manual testing. I was rather impressed with this unit, it was easy to install, the instructions are clear and easy to follow and with a price tag of £179.99 which includes two probes and all the kit you will need to get started I think it is a very good deal. I have used a complete set-up of the new TMC V2 range, calcium reactor, CO2 regulator with solenoid valve and the pH monitoring and controlling system, most of this equipment is brand new to the market and on initial inspection it looks good, I will keep you updated on how it all performs in later articles, more details on this equipment can be found at

I am using two 200w heater/thermostats to heat the water in the aquarium, in a centrally heated house and with the additional heat from the metal halides this will be adequate for this system. I always use two or more smaller heaters rather than one large one in any aquarium as the thermostats are prone to failing and if a thermostat sticks on you are not going to boil your tanks inhabitants if you use undersized heaters. The heaters have been fixed in the second section of the sump.

I have used lighting that I already had for this aquarium, namely a twin 250w Arcadia series pendant and T5 tubes. Four 54w T5 tubes were fitted close together in two reflectors, one for the front of the tank and one at the back. This was mainly done as the twin 250w halides did not provide enough light at the far ends of the tank due to the distance between the two lamps being too short. I already know how I want most of my aquascaping to be and the additional T5 tubes are able to contribute needed extra light especially at the far ends of the tank. The two T5’s at the rear of the tank will be white tubes and the two at the front of the tank will be actinic tubes. Although the actinic tubes will provide very little PAR in comparison to the white tubes or halides they will provide me with the opportunity to view the tank  with just actinics on late in the evening and give a spectacular view of the fluorescing colours of some of the corals.

The lamps that I am using are BLV 250w 10,000 Kelvin, I am using 10K bulbs rather than 14K bulbs as they provide considerably more PAR and reproduce more of the natural spectrum of light found on reefs.

Using a quantum meter I took some readings of light intensity throughout the aquarium. I should point out that the bulbs that are currently in the unit are over a year old and will be changed and that the water in the aquarium is RO water and has had no salt added so this will change the readings somewhat but I can get a good idea of what it will be. At the far ends of the aquarium (the last six inches) the light intensity under the T5s is over 100 µmol·m²·sec within the top six inches of water. This is good and well above the compensation point for many corals so I will have no problem stocking the shadier ends with lower light loving species.
Halfway down the aquarium (12” deep) and along the central three quarters of the tank there is over 500µmol·m²·sec and on the very bottom of the tank there is over 250µmol·m²·sec. I was surprised to see that the readings were so high, particularly as the lamps are so old and with new ones I would expect them to be up to 30% brighter. Perhaps the fresh rather than salt water is making a considerable difference, I will take some new measurements once the new lamps are installed and the salt has been added. If you are not sure what all these figures mean, for the most part corals cannot utilise light intensities much over 300µmol·m²·sec  and for many species light inhibition will start occurring at around 450µmol·m²·sec. Light intensities of less than 100µmol·m²·sec  will be below the minimum levels needed to survive, particularly for SPS corals.

All of the lights will be fitted with contactors and automatic timers set to illuminate the aquarium for twelve hours a day.

The system has now been filled with RO water and much of the equipment installed, I still have to sort out the pumps for the water movement within the tank and tidy up much of the electrics and cables but the next main stage of the installation will involve starting to mature the tank and getting ready for the aquascaping.