Building a Reef Aquarium Part 1

This feature will cover several issues and detail the construction and maintenance of a large reef aquarium through it’s design, building, stocking and maintenance over a period of almost a year. I will detail all of the considerations and techniques that I use to build and maintain a spectacular reef tank and hopefully provide some information that many of you will find useful if you are looking to install or improve your own aquarium.

Deciding What you Want
The first thing to do when thinking about installing an aquarium is deciding what you want to keep and what you want the finished tank to look like. For me that was easy – a large SPS dominated reef system. The alcove that the tank was going to be positioned in measured eight feet in length and about two and a half feet deep. I did not want the tank to take up the whole alcove as I needed room either side for equipment and water change systems and I also wanted the tank to be easily manageable, so in the end I decided on a 5′x2′x2′ aquarium and stand.

The Aquarium
I decided to purchase the aquarium and sta  nd from Seashell Aquariums (www.seashellaquariums.co.uk) they had been recommended to me by a long-standing member of the aquarium construction industry who had made many of the aquariums for my coral farming and fish breeding systems. Seashell Aquariums specialise in larger aquariums and I also wanted a cabinet that would stand thirty inches high and they were able to provide this. After checking out their website which included several aquariums designed for reef systems including those with closed loops and false backs I decided on a 60″x24″x24″ tank with a 30″ high cabinet in ‘Country Birch’ and a built in sump (figure 1).
I had decided to run the system with the Berlin method of live rock and protein skimming so needed the tank drilled with a hole to allow water to flow to a specially designed sump housed in the cabinet below. After speaking to the company I ordered the tank, cabinet and a sump that measured 36″x16″x17″ with dividers and weir systems built in to my specifications.
Shortly afterwards the system was delivered and I had the rather difficult task of getting it up the flight of stairs to my first floor lounge! The cabinet was easy but the tank with it’s 20mm base was slightly more difficult to say the least. After 30 minutes of much swearing, sweating, struggling and bruises three of us had managed to heave the brute up the flight of stairs and onto the stand in the lounge where we promptly all collapsed from exhaustion!

After recovering from my ordeal it was time to check things out and I have to say I was rather impressed. Both the tank and the sump had all of the glass edges bevelled giving the whole thing a luxurious finish. The cabinet was well thought out and made, all of the interior wood joints in the cabinet had been sealed with silicon to prevent condensation from entering and causing the wood to swell, the cabinet had also been constructed with large ventilation windows in the back to aid in the reduction of condensation. The cabinet also came with a frame hood that did not have any top to it so that I could use metal halide lighting suspended over the top of the tank. With the extra attention to detail and the price tag of £1,150.00 I was very pleased.

The Main Circulatory System
One of the first jobs to do was to plumb the main tank and sump together and install the return pump. The tank has a volume of 540 litres plus about another 80 litres volume for the sump giving a total system volume of 620 litres, knock off around 100 litres for water displacement from the live rock (although it will actually be more than this) and I have a working volume of 500 litres. When calculating the water turnover through the sump you should work to a minimum of six times turnover of water through the sump per hour, a much better figure to work with is ten times turnover per hour. This means that for a 500 litre system you should move 5,000 litres of water through the sump and back to the tank each hour. It is essential to know this when deciding on what size return pump to use and what diameter piping you need for your plumbing.
I wanted to use a submersible return pump rather than an external one so I went for the largest submersible Ocean Runner pump the OR6500 which would deliver a water flow rate of close to 5,000 litres per hour at the head height of 1.35m that I had. This would give me close to the ten times per hour turnover through the system that I wanted. I also needed drainage piping running from the main tank back to the sump that could deal with a flow rate of 5,000 litres per hour. I use ABS rigid piping for my plumbing and for the return drainage use a size of 60.3mm outer diameter which can easily handle 5,000 litres per hour through it.

There are lots of different ways that you can design your drainage system from your tank to your sump. You can have a weir system built into the tank which houses the drainage piping, you can have the base of your tank drilled or the side close to the water surface. Personally I always use a system where the base of the tank is drilled and utilise a standpipe to set the water level in the tank. I do this for a number of reasons, by having the base of the tank drilled with a standpipe fitted rather than an overflow hole drilled into the side or back of the tank close to the water surface I am reducing the risks of the drainage system blocking and causing the tank to overflow. I rarely, if ever bother with weir systems built into the tank, I don’t see any advantage to them and they take up a considerable amount of tank space without any real benefit.

One of the most important joints in a system is the one where the piping fits through the drainage hole drilled in the tank. If you get this wrong and it leaks then you are looking at some major problems. The correct fitting to use is a tank connector, this fits through the hole drilled in your tank and provides a connection for the rest of your piping. The tank connectors have a threaded end and a non-threaded end and two threaded nuts to fix the unit through your glass. These tank connectors come with a rubber seal but I always remove these as the rubber will eventually perish. Always fix your tank connector with the threaded end pointing downwards and seal the nuts onto the tank connector by running a layer of silicon around the thread, then use a layer of silicon around both edges of the nut that grip the glass. This will give you a solid and leak-proof joint provided you have run a good dose of silicon around all the seals. The picture in figure 2 shows the tank connector fixed and siliconed in place in the bottom of the tank.

Next I plumbed the standpipe into the tank connector and set the length of the standpipe so that when running the water level in the tank would be where I wanted it. When running the tank will have a water head of around 2-3cm so the length of the standpipe is cut so that it is 3cm shorter than where I want the water level to be. One of the problems with systems that have drainage running to sumps below is how to stop fish and other animals getting sucked down the piping. To solve this problem I made a baffle out of egg crate that fits around the top of the standpipe and will prevent any fish or snails ending up in the sump. The picture in figure 3 shows the standpipe fitted with the eggcrate baffle to prevent animals from going down the overflow pipe.

The Sump
When running the water flows down the standpipe and into the first section of the sump and in this first section I placed a fairly large volume of bioballs. These bioballs were not to act as biological filtration, bioballs and the like do make very effective areas for colonisation of aerobic bacteria but only when they are run in large trickle-style systems. The surface area of the bioballs is not that large (in comparison to other media) and when submerged they are not a particularly effective filtration media. The reason that I used the bioballs in this section is two-fold.

Firstly gaseous exchange, when the water enters the sump the water exits the pipe and is sprayed over several inches of bioballs that are built up above the surface of the water. As the water passes over the bioballs it is split into tiny droplets that greatly enhances the gaseous exchange between the water and the atmosphere. This is very important as it allows soluble gases such as carbon dioxide and nitrogen to be released from the water into the atmosphere and without it you are relying mainly on items such as your protein skimmer to provide places for this gaseous exchange to occur. This gaseous exchange helps to maintain a higher pH as carbon dioxide gas is released from the water readily and the water is sure to be oxygen saturated once it has passed through this section.

The second reason for the bioballs is to act as a bubble stop. As the water plummets down the drain piping and is churned around it develops large amounts of minute micro bubbles that can easily flow through the sump and be pumped back up into the main tank. These micro bubbles can irritate your corals causing them to stress and release mucus and in addition the micro bubbles can be very unsightly. The bioballs will help to prevent the micro bubbles from entering the next section of the sump.

Some of you may be thinking, that the bioballs will cause problems in the system as they will act as a ‘nitrate factory’, well there will be some nitrification going on there without any denitrification but it will not be to any significant level. In fact I will go as far as to predict that once settled this system will run with no detectable nitrates on a standard test kit (lets just hope that was not the kiss of death!). The photo in fig 4 shows the first section of the sump with the bioballs in place.
Once the water has passed through the bioballs it runs under the first divider and then over a further two weirs before entering the final section of the sump where the main return pump is located to pump the water back up to the main tank. These other sections of the sump and cabinet will house the other equipment such as protein skimmer, calcium reactor and the like but I will be covering these aspects of the reef system in the next article.

The return pump is plumbed in with rigid ABS piping with an outer diameter of 33.4mm. A T-piece was inserted in the piping just above the pump that leads to a hosetail fitting so that at a turn of a valve water can be pumped out of the system for water changes. The return piping was also fitted with ball valves to control the flow of water back up to the main tank, this can be seen in figure 5.
The return piping was split into two outlets in the main tank, one in the top right hand corner of the tank and the other in the top left hand corner, these can be seen in figure 6.

One of the safety aspects needed to be incorporated into the plumbing is to ensure that should the main pump ever fail then the water in the main tank does not back-siphon into the sump causing it to overflow. To prevent this happening the two water inlets in the main tank are positioned close to the waters surface so that should the main pump ever fail then only a limited amount of water can back-siphon into the sump.

The Water Change System
Now that the main tank was plumbed in I had to consider the water change systems and where I was going to house the electrics and water for the automatic top-up system. I had left myself space on either side of the tank so that I could build some further cupboard space to house these things. I obviously needed the cupboards to match up with the cabinet stand itself so I approached Seashell Aquariums again and they were able to provide me board cut to the dimensions that I needed and with the same wood finish that had been used for the tank cabinet. In fact they told me that this is a service that they provide regularly. The picture in figure 6 shows the cupboards that I built on either side of the main stand, the cupboard on the left to house the water change system and the one on the right to house the electrics and water for the freshwater top-up.

Water changes are an essential part of maintaining a healthy reef system but can be rather laborious and messy. Unfortunately this system is in a second floor lounge so I was not able to incorporate a fully automated water change system but I could include a partial one. In the cupboard to the left-hand side of the tank I installed a 24″x18″x15″ tank that is to be used for mixing fresh synthetic seawater for use in water changes, the tank is hard-plumbed into the main sump and will have a circulatory pump for mixing the water and pumping it into the main system during water changes. This can be seen in figure 7. The water change tank has a volume of 90 litres which means I can do almost a 20% water change in any one go with this system. Now that the main tanks and plumbing have been installed I can move on to the next stage of building the system. In the next article I will cover the installation of the hardware needed for maintaining much of the water chemistry and environment of the reef system.