Take Your Time When Designing Your Sump

In my opinion a sump is an extremely important addition to a [tag-tec]saltwater aquarium[/tag-tec]. Not everyone chooses to use one which is fair enough as this is down to personal preference but for me a sump has so many uses that the pros outweigh the cons.

Hide Equipment Out Of View

Without a sump then you would need to install the protein skimmer, heaters, nitrate filters (if required) etc either in or hanging on the display aquarium. You could of course partition a part of the display aquarium to hide this equipment but then you will be losing valuable space in the display aquarium. With a sump all of this equipment can be installed hidden from view in the sump.

Increase Water Volume

The more water that you have in your aquarium the easier it is to maintain [tag-self]water quality[/tag-self]. With a sump, dependant upon the size you will be increasing the amount of water in the system, therefore as long as you are careful it should be easier to maintain the excellent water quality which marine life requires.

Add Addition Filtration Or Nutrient Export Mechanisms

Aquarium filtration can be provided in many ways. There are preferred methods (like live rock and deep sand beds) and there are other methods (like canister filters, fluidised filters etc). I have my own preference but I would never push someone into using a type of filtration which they are uncomfortable with. All filtration works – it is the efficiency that counts. If your fish, corals etc are happy and thriving then who cares what filtration you are using.

With a sump however, no matter what type of aquarium filtration you are using you have the option to be able to add addition filtration to the aquarium system. You could install a deep sand bed into a partiton, perhaps a [tag-ice]refugium[/tag-ice] or you could even install a cryptic zone area if you so wish. The most common is the refugium as this acts as a fantastic device to reduce phosphate and nitrate levels in the aquarium.

So you’re sold – you want a sump – what next?

First of all you need to work out where the sump is going to be sited. The majority of aquarists choose to locate the sump underneath the display aquarium hidden from view in the aquarium cabinet. It does not have to be installed there though it can be installed anywhere where you can get water to it from the display aquarium and back again. It could be in the adjoining room, above the aquarium, next to the aquarium – your choice.

Once you have selected where the sump is to be located the next aspect is what size, shape and type of sump. Personally I would recommend that you go for the largest sump as you can fit. There are many aquarists nowadays who have a sump (in some instances more than one) which is larger than the actual display aquarium itself. The benefits of a sump as detailed above merit the reason for the choice of a large sump. Next is the shape – again this is up to you and need to be relevant to where the sump is to be located. The type of sump is a strange one as a lot of people believe that a sump has to be an aquarium (glass or acrylic). A sump can be made from anything which is classed as ‘food grade’. Being of ‘food grade’ quality means that it will be safe for use with saltwater and should not leach anything detrimental into the water.

Once the above is decided and possibly the sump has been purchased then the next thing to do is decide if you want to partition the sump at all. If the sump is to be used purely for hiding equipment and/or for increasing water volume then there will probably be no requirement to partition the sump. If, however you want to utilise the sump to increase filtration capabilities or add additional nutrient export mechanisms then your sump would benefit from partitions.

There are no set rules when it comes to partitioning the sump. The rule of thumb I use is that I want to achieve the largest possible surface area for the filtration/nutrient export. What I normally do it split the sump into three separate chambers. The first is where the water enters the sump from the display aquarium, the second is the filtration/nutrient export area and the final chamber is where the equipment including the return pumps is located.

I size the first partition so that the overflow pipes just fit. I then move onto the third chamber. I measure all the equipment which is to be housed in this area and move the equipment around until I have a suitable design which takes up the least space whilst still allowing me to gain access to the aquarium. In then size this third partiton to be this size. Between the first/second chamber and the second/third chamber I then either install a baffle or an overflow. The reason for this is that the one between the first and second prevents any bubbles getting into the second chamber. The one between the second and third chambers prevents any large particles (algae etc) from getting to the return pumps.

Sizing the sump this way allows me to have the largest possible surface area for the filtration/nutrient export. No matter how the partitions are placed I will still get the same amount of water volume increase so I want to ensure that I get the maximum amount of filtration space as possible.


If you choose to design and partition your sump yourself then take your time in the planning stage. If you find out at a later stage when the sump is full of water etc then it is to late to change it. I personally use a product called Google Sketchup for this. You can create various designs based upon various measurements and then build your sump based upon the plan.

Remember when sizing your final chamber where the equipment is going to be located that you are going to need a return pump (unless the sump is above the display aquarium). You don’t want to partition it all up – install the skimmer etc and then find that you do not have enough room for your return pumps!

Using [tag-self]aquarium sealant[/tag-self] is not that hard as long as you take your time. If you really struggle at DIY then pop along to your local fish shop. I am sure that either they will be able to do it for you – if not then they will probably know someone who will.

Remember that when you fill the sump that if the power goes off in the display aquarium that water will still continue down to the sump via the overflows until the water level drops beneath the overflow. Therefore make sure that you do not fill the sump right to the top otherwise you are risking a small flood if a power cut does happen.

For inspiration here is a link to a sump design which I believe is fantastic :


And from the site another type of sump design which is called a tower sump :


Interesting Reading From Across The Blogosphere

diy reef sump build – This made it a very simple DIY sump. (We ordered the glass from Torstenson Glass. If you are in Chicago, we highly recommend them.) To start we cleaned all the glass with rubbing alcohol to remove any oils from our hands. …

  1. Interesting article about aquarium sumps and needs. Good job!

  2. Thanks for that, appreciated.

  3. hi i am just starting to look at installing a sump for my marine tank which has been up and running for about a year , i have a V2 Vecton 200 ultraviolet water steralizer and a V2 react 600 calcium reactor with c/o2 system, how would I incorprerate this into a sump setup your help is greatfull

  4. Hello Alan. Adding a sump to your system is a good idea – it gives some extra seawater volume and also somewhere for additional filtration, plus a place to put ‘unnatural looking stuff’ like heaters etc.
    As far as the ultraviolet sterilizer and calcium reactor are concerned only you can decide the actual physical location of the equipment itself, some equipment types can fit inside a sump but often they fit outside. The intakes and outlets can be placed in a sump. In my opinion it’s best to place inlets to both the sterilizer and reactor after any initial filtration area that is incorporated in the sump, usually where this occurs the sump is partitioned. (A basic partitioned sump has three partitions, the first is for incoming seawater filtration, the second is an open area where there could be, for example, a deep sand bed, and the third contains the return pump.) This helps to ensure that the seawater delivered to the equipment is clean. The outlets from the equipment should go where the seawater is pumped back up to the display aquarium. Remember to use a pump that is suited to the UV steriliser, the correct flow rate ensures that any nasties are properly exposed to the UV radiation and thus either killed or damaged. Calcium reactors usually take some fiddling to achieve the correct rate of input to maintain the levels required.

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