Tenji is pleased to present a series of exclusive articles for Reef2Reef members. We will be delving into the various aspects of reef keeping, focusing on tried and true methods that can be implemented by aquarists of all levels.

Once you have chosen your display aquarium and paired it with an appropriate top, the next step is to pick out your sump. Sumps offer a space to hide equipment, and generally speaking, make keeping a reef tank significantly easier than trying to hang everything off the side of your aquarium. Oftentimes you can even perform your water changes exclusively from your sump (still have to maintain substrate – more on that in a future installment) which will help prevent stressing out your animals or exposing coral to low-tide.

There are five main options for sump material: glass, acrylic, polyvinyl chloride (PVC), high-density polyethylene (HDPE), and fiberglass. Pros and cons listed below.

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Glass Sump Pros

· Very affordable

· Easy to customize

· Easy to find

· You can snag a small glass tank from nearly any pet store that could function as a sump

Glass Sump Cons

· Easy to break

· Not a great thermal insulator (heater/chiller will run more)

· Generally only basic baffle design is available

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Acrylic Sump Pros

· Fairly affordable

· Nearly limitless customization

· Better insulator than glass

· Lightweight (compared to glass and PVC)

· Much sturdier than glass (assuming suitable material thickness)

· Can include cool colored options

Acrylic Sump Cons

· Generally more expensive than glass

· Longer lead times for custom designs

· Sometimes have to pay for shipping

· Not as efficient insulator compared to PVC

· Not as sturdy as PVC or HDPE

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PVC Sump Pros

· Top notch structural integrity

· Excellent thermal insulation

· Limitless customization including full exposure UV baths

· Industrial look and feel – you can tell friends and family this is what most public aquariums use

PVC Sump Cons

· Expense

· Longer lead times than off-the-shelf options

· Quite heavy compared to other options (due to sturdiness of material)

· Must be shipped freight

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HDPE Sump Pros

· One-piece molded HDPE sumps are very sturdy (no seams to fail)

· Welded HDPE sumps are still very robust

· More affordable than PVC and sometimes acrylic

· Large sizes can be had for minimal expense

· Lightweight compared to PVC

HDPE Sump Cons

· Limited suppliers and size options (unless custom which removes affordability aspect)

· Difficult to customize molded HDPE

· Not a great thermal insulator

· Generally shipped freight

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Fiberglass Sump Pros

· Fiberglass sumps are as close to indestructible as you can get

· More affordable than PVC and sometimes acrylic

· Fairly lightweight

· Great thermal insulator

Fiberglass Sump Cons

· Limited suppliers and size options (unless custom which removes affordability aspect)

· Difficult to customize without glassing experience

· Generally no baffles are pre-installed

· Not a great option for sub 500-gallon systems

· Must be shipped freight

Most hobbyists will find a great option in acrylic sumps. If you drop a pump or accidently kick it, you won’t be too concerned of breaking it as with a glass sump. These sumps will have a long lifespan and will accommodate most methods of running a reef tank. Nowadays there are color options to fit any motif should you want to pop the hood and watch your fellow reefers drool. Here are the basic aspects we look for when choosing a sump:

· KISSKeep It Simple Stupid. Don’t overcomplicate your sump design. The less baffles, chambers, etc. you go with the easier it will be to keep your sump detritus free, along with affording more room for expansion down the line for new methods and equipment.

· Material thickness – the thicker the material the better. Thicker material affords a better bond, and better shock protection from dropping a pump, kicking it, etc. The thicker it is, the longer is will last.

· Bracing – just like with a display tank it is imperative that your sump panels do not deflect. Thicker material will help with this, but a solid one-piece euro brace will really add structural integrity. A euro brace will also keep splashing and salt creep to a minimum.

· Size – go with the largest sized sump you can afford, however, don’t forget to leave room for an auto top-off reservoir, two-part reservoirs / calcium reactor, or any other external equipment. Of course, you’ll also need room for all the electronic components too (ballasts, switches, controllers, etc.). We aim for a minimum size of 20% of the display tank volume.

That wraps up the basics on sump materials and their advantages/disadvantages. If you have any questions or would like us to help you with your next sump design, please do not hesitate to reach out!