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There are few things that can benefit an aquarium, particularly a salt water aquarium, as much as a good sump. Sumps allow you to create an entire system separate from the main tank that contains all your water processing, heating, conditioning and so on without crowding or visually afflicting the main tank; they allow you to add chemicals and treatments to the water and have them pre-mixed with a large volume of water before they reach your aquarium’s inhabitants, and much more.

But traditional sumps require expensive main tanks with plumbing ports (you can’t add ports to your typical large, inexpensive aquarium, as they are inevitably built with tempered glass), and are mounted underneath the main aquarium where they require bending over to service. Both of these issues go away with this design. You can use any non-ported aquarium as your main tank, so that $500, 75-gallon aquarium with stand from Petsmart you’ve been eying is just fine, and the sump is above the tank, perhaps on a floor above, where you can actually get at it and maintain it.

Here’s my design. You are most welcome to use it.

First, you may want to click on this plan so you can refer to it, and this plan as well if you’d like to build a fail-off pump controller. All of the picky design details are in the plans. The discussion here will be an overview.

You should know that I have built this design, and it works extremely well. It is safe in terms of overflow, reliable in that it will safely do its job with no unusual maintainance (no system can avoid the maintainance required to keep pumps, pipes and valves in good shape), quiet, and considerably less expensive than the more common approach: setting up a sump below the main aquarium.

You’ll need a cheap aquarium of a size sufficient to contain the volume of water you want in the main, active chamber of your sump, plus three chambers as wide as your fist in its long dimension. The additional volume is used for smaller anti-siphon, pre-filter and anti-drain chambers. They are much smaller than the main chamber, but I like them large enough to allow me to get in there and clean them, so I designed mine to be about as wide as my fist. You could go smaller if you are willing to do all your cleaning with a brush on a handle. I don’t recommend it. A fist width is about the best compromise.

The main build: Once you begin working on this, you’ll be using plexiglass and silicone in chamber construction so you’ll need a way to cut the plexiglass to size. Various types of saws will do the trick. You’ll also need some diamond hole saws to provide for two ports in the sump (not the aquarium); you can buy them on Amazon for very little money.

Cutting ports with diamond hole saws: You need two ports. One at 1/2 way up from the sump bottom on the end, and one at 3/4 of the way up from the sump bottom (or 1/4 of the way down from the sump top) on the same end. Don’t go any closer to the edges of the pane of glass, or it will simply break when you try to cut it.

You’ll need gloves and safety glasses. Really. This kind of glass cutting isn’t all that difficult, but fail to take these simple safety precautions and you may end up in your hospital’s emergency room with a very serious injury or injuries. Think about high-speed flying splinters of glass and assume the appropriate amount of caution before you start any glass-cutting projects.

To accomplish the hole cuts, take the soon-to-be-a-sump outside, have someone turn a hose on it with considerable cold water flowing, and slowly and carefully begin each hole cut by slowly bringing the diamond hole saw to the surface of the glass at a 45 degree angle. Do NOT press hard. Let the saw’s rotation do the cutting, not downward pressure. As soon as you have cut a little bit into the glass, slowly begin to lean the saw over with the ultimate objective being to get it where the saw is essentially flat or nearly so to the glass and cutting all around the perimeter of the saw instead of just on one edge. PROCEED SLOWLY. I can’t emphasize this enough. This process makes a LOT of heat and you need to give the cold water the time it needs to carry that heat away or the glass WILL break. In addition, too much force and the glass will break from the pressure you’re applying and then you’ll need a new sump tank. Also the faster you cut, the more the likelihood there is that you will produce dangerous glass splinters. PROCEED SLOWLY!

Filtering: I like to use inexpensive commercial filter cartridges, but as I think is pretty obvious, you can modify the design of the filter panel and associated chamber to accommodate whatever you want to use without otherwise affecting the sump as long as you don’t change its overall height.

Plumbing: You’ll need flexible hose (probably 1 inch hose) and associated fittings. All fittings for running the pipe except right at the sump should be of the “barb” variety, which allow insertion directly into the pipe. Likely the ports you buy will be slip fittings, so you’ll need PVC primer and glue for that. If you end up using any threaded fittings, you’ll need adapters for that. Look at your planned installation and map out exactly what kind of turns your plumbing will have to accommodate. Obtain elbows, connectors, adapters and filter screens as required.

Typically, you’ll need three screens: one for the intake to prevent large items from being sucked into the system; one for the main outflow to prevent critters from swimming upstream into the sump, and one on the overflow for the same reason. All of them go on the pipe ends at the main tank.

You’ll need one gate valve. Don’t buy a ball valve. Ball valves are almost always less expensive, but trust me: that’s a false economy in this case. Gate valves are vastly superior for the job the valve has to do here, which is a fairly precise and easily adjusted control of water flow. Buy a ball valve instead, and I promise you’ll regret it. First time around, I bought a ball valve. And I ended up replacing it with a gate valve. It was terrible.

You’ll need a pump that can handle the head (water lift height) of the design and still circulate the volume of your aquarium seven to ten times an hour. For instance, I just built a 75 gallon system, so I needed between 750 gallows per hour flow at the top end, to a minimum of 525 gallons per hour. I found a pump (a Pan World 100PX-X) with a rated max head of 13 feet at 1270 gallons per hour, which is a GPH rating they provide assuming no head, or lift height. Great pump, by the way: quiet, runs cool, not unreasonably priced.

My lift height (where to measure your lift height is detailed on the sump design) is 80 inches, or 6.7 feet. De-rating the pump’s GPH is easy enough; it’s the lift height divided by the max head, times the GPH. Circulation is then that result, divided by the tank volume. In my case:

    Lift Derate: 6.7 / 13 = 0.515
    Circulation: 0.515 x 1270 = 654.5 GPH
    Cycles/hour: 654.5 / 75 = 8.72 times per hour — excellent.

So with the sump built as shown, emplaced as shown, the rest is all about how you route your plumbing. That will vary with your needs, so I can’t offer much advice other than to say never let the flexible hose turn corners for you. It’s not that flexible, and it will tend to collapse due to the bend, which is a Very Bad Thing. Use elbows. They’re only about a dollar or two each, and they make your plumbing reliable, which it seriously needs to be.

One difference between this design and a below-mounted sump design is that mounting below makes your main aquarium constant volume, which means that evaporation and water addition change the level in the sump, not the main aquarium.

With an above-mounted sump, it works the other way around: the sump is constant volume and the main tank changes level with addition or evaporation.

Personally, I find this difference to be of absolutely no consequence, as uncompensated evaporation causes the salinity to change, which you really want to avoid, so it’ll never be a serious issue. Conversely adding water is only required for water changes where you’re going to get the tank level just where you want it anyway, or to compensate for evaporation which as I say you need to stay on top of anyway.

Have fun, and of course if you have any questions, post them and I’ll do my best to answer them. If you have no questions, just keep in mind that getting this right was a matter of some very narrow-range-solution design issues. Don’t change anything other than the filter panel design and expect the sump to work properly. It almost certainly will not. If in doubt, by all means, ask me. I’ve already made just about every mistake you can imagine. No need for you to repeat them!

Read the commentary on the design sheet carefully, please. I’ve tried to explain the whys and wherefores of each element. But again, any questions, just ask.