On a large aquarium sumps have practically become a requirement.

What purpose does a sump serve?

There are many benefits. Sumps are typically much larger than canister filters or other filter solutions that might be used in an aquarium. This larger size is the primary benefit that comes across many different ways:

  • Larger volume of filter media (cleaner water)
  • Larger water volume means more stable parameters (problems develop more slowly)
  • A place to hide equipment (filters, heaters, chillers, probes… etc. Nicer looking tank)
  • A separate place to grow visually annoying but helpful things like certain algae
  • A safe location to isolate a problematic fish
  • Easier access for maintenance tasks without disturbing the tank inhabitants

This is only a partial list. Sumps almost feel like a golden ticket.

How do sumps work?adv300

A sump is typically installed below the display tank. Water is moved circularly from the display tank to the sump and then back again. You can learn more about the different systems of moving water to/from the sump in another post.

The process is quite simple: Control the flow of water through multiple compartments that serve different tasks. Eventually the water is returned to the main display tank via a pump.

Each section of the sump typically serves a specific purpose. It might be to filter the water, or provide biological additions (a refugium growing healthy algae). Refugiums will be covered in a future post.

Why seamless sumps?Aquarium-Sump-Filter-Sock-Baffel-Resevoir-Tub-1SB-BE-1RE-Angle

There are dozens if not hundreds of commercially available sump designs. In addition, sumps are simple things. You can build one yourself that will be just about as effective as commercial options (perhaps better, more on this later).

Seamless sumps is different in that each section of the sump is a separate container. This allows you to modify your sump design over time by adding or removing additional containers.

Simple modularity

It consists of 3 basic tub types pictured in the image. The first is a sock tub which performs mechanical filtration. It is available in 3 different sizes.

The second is a baffle tub. This supports biological and chemical filtration as well as a location for return pumps.

The third is a reservoir tub. The two primary uses is an evaporation section or a refugium section.

Each section has many alternate configurations. And in fact, you can use any of them for any typical sump task.

The different tubs are linked using a cross tube to allow water to flow from one section to the next. Depending on how each section is configured and how it is linked will determine what it can do.

For example, a reservoir tub linked at the top will act as a refugium as the water level will remain high in that tub. The same tank linked at a lower level will act as an evaporation tank. This will add a large volume of water to the connected tank and act almost like a simple auto top off system.

You can see many of the different sections and combinations here.

Upgradeability is king

The ability to arrange the sections to fit your needs makes it possible to grow your sump as you grow your tank. To start with you might do a simple freshwater tank with just mechanical and bio filters. Later you might convert that tank to a saltwater and add a refugium.

A few years later you might want to upgrade your display tank from your starter tank to something larger. At this point you will be able to add to the seamless sump rather than replacing it. Adding an ATO (or a simple evaporation reservoir). Expanding to a multi-tank refugium or adding more filtration will also be simple.


As a beginner, I find this particularly appealing. I don’t know if I want a refugium or what I might want in it. If I use this system, I can add a refugium later when my tank water parameters may require these changes.

This is the only sump I’ve found thus far that allows me to start with a simpler setup and add more complexity later. In all other cases, I have to buy the biggest thing I think I might need, or replace the entire sump later when my needs change.

The material may also represent some advantages. Very little sticks to the surface including algae. It should be easier to clean. As a single piece of plastic, the only place it can leak is where you join the tubs together. It should last years.

Since it is created out of sections, it is likely you can get it into stands with small doors and no side door.


I have not seen in sump protien skimmers (more on skimmers in a future post) used in this sump. Currently i am not a huge fan of out of sump skimmers. It’s not that you can’t use an in sump skimmer but it would require a whole section dedicated to the skimmer (and there are size restrictions) which seems wasteful compared to just using an out of sump skimmer model. There is a larger filter sock tub that can be combined with some in sump skimmers. It will depend on your skimmer size.

Initially I thought this modular system would save on upfront cost. Unfortunately, the pricing for these modular pieces is a bit high. I want to qualify that, as I know the price of these systems is something others have liked. I am new to the aquarium hobby. I am comparing this sump to something like an Eshopps ADV-300 pictured above. That sump typically sells for $550 online. The “equivalent” seamless easily starts at $565 without the necessary essentials. I’m not trying to compare these sumps from a functional view point. I don’t have the necessary experience for that. I have a feeling the seamless is far superior. But the price is a bit of a system shock for a new aquarist, especially then an Eshopps R-200 for around $300 would do what I need. I am not trying to compare it to any of those $4,000 sumps. I’m looking for something I can actually have in my house.

Additionally, due to the modular design, space is wasted between pieces. This space adds up and that same 3 section seamless sump will not fit in the 48 inch stand I had originally planned.

You also have to do a small amount of work to plumb the sections yourself if you don’t order it pre-built. This is not a huge deal and is certainly easier than building your own glass/acrylic sump.

The HDPE material creates some questions for me that I will cover in an upcoming post.

That said, I like this sump so much, I’m considering a different shape tank and stand so I can eventually install this sump system. I’m even looking at other costs I can eliminate. I may even do a 2 section seamless sump to control cost initially.

The DIY optionSump48x12x16_2015-Dec-31_02-34-03PM-000_CustomizedView21527440

The rendering to the right is a sump I am designing to save money. The outer tank will be a stock size purchased from my local fish store. I will install the dividers to create the various sections I think I’m going to want. (3d modeling/design is another hobby of mine)

This solution will be a lot more work. But it has the advantage of fitting my needs now while not costing a lot of money. In fact, the cost will likely be a fraction of any equivalent commercial solutions and will have exactly what I need. The problem is if my needs change, I have to replace the sump.


If money were no object, I would probably buy the seamless sump in a heart beat. I like having long term flexibility. And if my tank stand were big enough, I would stuff it full of seamless sump sections.

The video below shows a 4 section seamless sump. That is an enormous tank above it. It shows the sheer size of the sump. This also happens to be the seamless sump design I want to eventually achieve.

What do you think about seamless sumps?

Here is a video about the sumps: