How to Design a Reef Tank Sump

Why Did I Start To Redesign The Sump for My Reef Tank?

In short, it was a long time coming. As I purchased more equipment like the Neptune Apex, Trident, a new Protein Skimmer, and even built an Algae Scrubber, it became obvious that the sump was pieced together. There were multiple pumps that pulled in water from the first chamber but would add it back to either the last or just before the last chamber. Entirely bypassing the heaters, sensors, and protein skimmer.

As I write this, I think back to other changes including switching my refugium from sand to reef mud, and switching over to kalkwasser instead of using 2-part solutions. This isn't even the end of the list, and this particular sump hasn't even been up for a year. So now is a great time to look at the sump design retrospectively.

The Straw That Broke the Camel Shrimp's Back...

The event that made me realize I need to look at making some changes was when I needed to make a small change in the refugium. I decided to clean up the refugium to allow the cheato algae to tumble. While removing extra rock that wasn't providing much surface area, the mud in the refugium was disturbed. This led to the entire system becoming a muddy mess. You couldn't even see the fish. This lasted for 2 days before it settled. Even though very little settled in the rock thanks to the powerhead flow, there was still some mud that settled in the sand, meaning more cleaning...

Even worse, EVERYTHING in the sump was covered in mud. Every pump, filter, surface, everything. And even with the less cluttered refugium, the cheato still can't tumble because any flow in the refugium chamber will stir up more mud. Now it's time to make a change!

Cleaning Out the Sump

Cleaning out the sump was actually easier than expected. After turning off and removing all of the equipment, I was able to scoop out the mud out. Then I used a utility pump to remove most of the water. To get the remaining debris and mud, I used a shop vac. If you don't have one, a shop vac is one of the best cleanup items to have on hand for accidental spills or cleanups like this.

Reef Tank Sump Design

Before we compare the best options for filtration, we need to think about the sump design. If you haven't already, this would be a good time to read my Guide to Saltwater Aquarium Filtration.

The Goal - Why Do You Have A Reef Tank Sump?

The purpose of the sump for the reef tank is to remove the filtration and equipment from the display aquarium, and provide an ideal location for filtration and equipment. The sump can be thought of as being the collection of vital organs for your reef tank. Even better, think of the sump as a one-stop filtration center and control center for your reef tank.

Some of the responsibilities of the sump include:

• Large Particle Filtration
• Small Particle Filtration
• Biological Filtration
• Reef Tank Heating / Cooling
• Aquarium Water Topoff
• Balancing Parameters - Alkalinity, Calcium, Magnesium, etc
• Providing Oxygen to the Reef Tank
• Optional - Monitoring Parameters
• Optional - Ideal location for water changes

As you can see, the saltwater aquarium sump handles a lot. Yet we usually just buy a sump "as-is" and start adding equipment as we go. I know that's what I did. So I decided to rethink the design and make the sump an ideal filtration system and control center for my reef tank.

Step 1: What Do You Have to Work With?

This is when you should grab a pencil and some paper. Let's start by sketching out what your sump looks like. What chambers are there and roughly where are they. This gives us a blank canvas to work with and design a sump that works perfectly for your reef tank.

After this, I like to think through each step of the sump one at a time. Each of the reef tank sump's responsabilities have a number of options available and it is worth considering each option.

Step 2: Large Particle Filtration

Large particle filtration is the step where the reef tank sump removes large waste particles such as hair algae, extra food, fish waste, sand, and a number of other large waste that could make its way down to the sump. The intention is to prevent any large particles from making it to the pumps and other filtration. Additonally, removing this waste before it can break down and increase ammonia, nitrite, nitrate, and/or phosphate levels.

Even though the filter media catches the waste before it makes its way to the other equipment, the waste needs to be removed from the water before it can break down in order to be effective. Removal needs to occur every 2 to 3 days to achieve this. Some filtration options I will discuss will automatically do this for you, but some require you to remove and clean the filter media yourself. You will need to be honest with yourself and ask yourself "Will I ACTUALLY change the filter EVERY OTHER DAY?". For most of us, myself included, we think the answer is yes. For a while this may happen, but over time, the reality is likely not. Remember that reef tanks are about the long term, and you should do what makes sense long term.

Filter Floss [Bad...]

I was going to start this section with a "good, better, best" approach, but filter floss doesn't even make the "good" category. Filter floss will catch large particles of waste, and is cheap initially. Unfortunately, the reality is that you will likely not be able to clean filter floss and it will be better to simply throw it away every other day. If you are replacing the filter floss this frequently, it's no longer cheap. Plus, it is VERY unlikely that you will do this long term. So let's not even consider Filter Floss in your reef tank sump design.

Filter Pads [Good?]

Filter pads are not an ideal solution, but definitely better than filter floss. You can cut the pads to a specific size and stack them in a chamber in your sump. This will force the water to flow through them. There are also pads that contain absorbing material to help remove things such as phosphates from your reef tank. Additionally, the filter pads are easily removed for replacement and/or cleaning. Like filter socks, filter pads should be removed and either replaced or cleaned every 2 to 3 days. Otherwise any debris caught in the filter pad will break down and add Nitrates and Phosphates to your reef tank.

Filter Socks [Better]

When it comes to large particle filtration, filter socks are one of the 2 best options available. Filter Socks are low cost, easy to clean, and catch a large amount of the waste you are looking to filter out. If you buy 7 to 14 filter socks, you will only have to was the filter socks once or twice per month. Just pull the dirty socks out, turn it inside out (over a trash can), and let it dry in a 5 gallon bucket until you are ready to wash a load of them. The best part is that at about $6.00 USD per filter sock, it is only $42.00 to $84.00 to purchase the filter socks and about $20.00 USD for the filter sock holder. Making this a very affordable and GREAT long term solution. As long as you are going to change the filter sock every other day.

Automatic Filter Roller [Best]

The filter roller is the most modern reef tank sump innovation in quite some time! The filter roller implements all of the benefits of the filter socks but instead of replacing the filter sock every couple of days, the automatic filter roller will roll up the waste and put fresh filtration as it is needed. All you have to do is replace the filter roll as needed. It doesn't get much simpler than that!

Reef Stable Recommendation

When it comes to nutrient control, an ounce of prevention is worth like 1 ton of cure. If you could prevent ever having high nitrates and phosphates, why wouldn't you? As such, the Reef Stable Recommendation is strongly for the automatic filter roller. If you don't have the money for the filter roller at the moment, filter socks are the next best choice!

Shop Automatic Filter Roller

Shop Filter Socks

Step 3: Small Particle Filtration

Small particles are anything that make it past the filter socks / filter roller. This is usually 200 microns or smaller. There are a couple of methods of removing these small particles, each with their own benefits.

Activated Carbon Filtration

Activated Carbon, especially ROX 0.8 Activated Carbon, is a well known method of removing very small particles from the water. The particles flow into the carbon and get trapped within the small pores of the carbon. This carbon will then need to be replaced when it becomes clogged. Activated Carbon is often used to "polish" the water. This is because of how effective it is at removing these small particles from the water. However, if the carbon becomes clogged quickly, it can become expensive.

There are a number of ways to use activated carbon. The most popular seem to be hang-on-back filters and activated carbon reactors. Both options work very similarly, however the hang-on-back option is quite limited. There is generally a small amount of space and the pump is part of the filter itself. Activated Carbon Reactors, or media reactors, allow you to choose the amount of filter media being used, as well as choosing which pump you would like. Giving you more control over flow rate.

Protein Skimmers

Protein Skimmers are one of the most cost effective methods of removing small particles from the water. Using a large amount of micro bubbles to force small particles up to a collection cup; where you can remove it from your tank forever! There is no filter media meaning it is a one time cost! Now, I am not going to pretend that the protein skimmer can remove extremely small particles as well as activated carbon, but it can GREATLY reduce the amount of particles that enter the activated carbon. Saving you money on on replacing activated carbon!

If you use a protein skimmer, you don't have to also run activated carbon. However, it doesn't hurt to use both. It will simply make your reef tank water cleaner.

An added benefit of the Protein Skimmer is that it removes the excess CO2 from the reef tank. By adding oxygen to the water, it will help your fish breath, as well as raise your pH! Making protein skimmers an easy choice in terms of benefits for the price!

SHOP PROTEIN SKIMMERS

When choosing a protein skimmer, they always have a tank size rating. Usually, this number is high. Always aim on the side of "Heavy Bioload" or "High Stocking". Though your reef may be lightly stocked for now, there is no telling if you will need more power down the road. If you can spend the extra money, a DC Protein Skimmer allows you to dial this in better. Meaning an over-powered skimmer can be dialed down with ease. AC skimmers also allow you to dial down but they are limited in this control.

Reef Stable Recommendation

I think the answer speaks for itself... Why not both! The benefits of the protein skimmer make it a clear winner, but why not take advantage of the added benefits provided by ROX 0.8 Activated Carbon? I would recommend using a media reactor for holding the activated carbon, giving you the most freedom as your tank matures.

Step 4: Biological Filtration / Nutrient Removal

Now for the smallest particle removal, nitrates and phosphates. Once nitrates and phosphates are in the reef tank, they can be very difficult to remove. You will also likely notice algae growth in the reef tank. There are a couple of ways to combat the nitrate and phosphates in a reef tank.

Refugium

The most common method of nutrient removal in reef tanks is to have a refugium. A refugium is a section in the reef tank sump where biological filtration and macro algae can live. The most common setup includes a deep sand bed, live rock, and chaeto as a macro algae.

Other refugium methods include reef tank refugium mud, Mangroves instead of Macroalgae, and even the use of different types of macroalgae.

For more information about refugiums, check out the article Saltwater Refugium - What are They and Do I need One?.

Clean Refugium Approach

In an attempt to progress forward in the reef tank hobby, I have decided to take it a step further with the "clean sump" approach. I am utilizing newer technology and products to prevent a messy sump. This means no substrates and less to clean. The downside is with less work, comes a higher price tag. Though more expensive, you can prevent a large amount of cleaning and trying to identify nitrate traps in the future.

After the mud incident mentioned at the top of this article, I have personally tried to stay away from substrates in the reef tank sump. However, I added a large number of bioballs to provide the surface area needed to help remove these nutrients from the tank, without the mess.

Algae Scrubber

An algae scrubber is simply a sheet or sheets with strong lighting that is easy for algae to grow on. This algae will consume nitrates and phosphates as it grows. When you remove the algae from the algae scrubber, the nutrients will be removed from your reef tank for good!

There are a couple types of algae scrubbers, in water and out of water. The out-of-water scrubbers have water flow over a textured sheet and then the water flows back into the reef tank sump. Underwater varieties often use air stones to pull water across a sheet in an enclosed area where the algae grows. Either option will work, and both have professional products available as well as DIY options. If you have the ability, the professional products will work significantly better, but there is a higher price tag.

SHOP ALGAE SCRUBBERS

Bio Bricks and Bio Media

Bio Bricks and other bio media provide a large amount of surface area where the bacteria that consumes nitrates can live. The bacteria then absorbs the nitrates until they become large enough that the protein skimmer can remove them. If you have the space, using bio bricks as a stand for your skimmer is a common approach to adding surface area to a clean reef tank sump, without adding sand or live rock that may take up much more space and require more maintenance.

Reef Stable Recommendation

For removing nutrients from your reef tank, I am becoming a fan of the clean, technology and science based methods. If money is not a concern, I would recommend utilizing Bio bricks and bio plates to provide far more surface area for nitrates to be removed from the reef. Additionally, the algae scrubber provides a very clean look for growing algae and removing nutrients from the aquarium.

I am aware that these can be very expensive. Because of the large price tag, if you choose to wait on the algae scrubber, you can simply grow macro algae such as chaeto. These algae are very good at removing nutrients and are much lower cost. In fact, this is what I am currently using in my sump, until the price of algae scrubbers comes down.

Step 5: Reef Tank Heating and Cooling

The next responsability for the reef tank sump is to maintain a constant temperature for the saltwater aquarium. For most, this only includes heaters, however, if the room where the reef tank is located can reach 80 degrees F or more, you will want to utilize a chiller as well.

Reef Tank Heaters

There are a number of types of reef tank heaters, including plastic, glass, and titanium. Some have built in temperature controllers, and some you need to buy a temperature controller to work with the heater. In terms of which heater setup I reccommend, get yourself two titanium heaters. I choose titanium to prevent breaking the glass ones under water, which could lead to other problems. Having two, each being about half of the total power needed, will provide redundantcy in case one fails. It also splits the power load across multiple outlets. You will also want an external temperature controller to provide accuracy and redundant control for your reef tank.

As for placement, you will want heaters to be located directly in the flow in a location where all water has to move. The heater must be completely submerged in water at all times as well. This means the ideal location is in a baffle of your sump where the opening is at the bottom. This will force all water to flow over the heater as well as keeping it underwater.

I'll admit, I didn't get too deep into identifying what heater you will need. That's because I have a resource, Simple Rules for Picking a Fish Tank Heater that helps walk you through exactly what you need to heat your reef tank!

Reef Tank Chillers

Reef tank chillers are essentially an air conditioning unit for your reef tank. If you live in an area where it is possible for the space near the tank to be above 78 degrees F, you may consider having a reef tank chiller. Living in Wisconsin, having my aquariums in the basement, this seems like it would never happen. However, I have forgotten that windows were open and it has gotten very close in the summer.

Reef tank chillers are very expensive, but can save your aquarium if/when something goes wrong. Most of us use an air conditioner to ensure the temperature in the room won't be above 80 degrees. However, if you lose power, or your air conditioner fails, the chiller (and maybe a generator) could save your entire reef!

SHOP REEF TANK CHILLERS

Insulating the Reef Tank Sump

Insulating your reef tank sump is not a replacement for heaters nor chillers. Let's just get that out of the way. They can save you money in maintaining the temperature of the tank though. A prime example is my reef tanks. My aquariums are in the basement in Wisconsin. Needless to say, it gets cold in the winter... In fact, there was a point where I had 2, 500 watt heaters that were on almost 24/7. I don;t even want to talk about the electric bill from that...

Something I did to help with this was wrapping the sump in foam insulation board. I even found a foam board that was strong enough to sit under the sump without crushing. You may want to avoid this however, because if the sump is not level, it could cause the sump to break an lead to a large problem.

For the display tank, you may consider a painted foam board on the back and sides of the tank that are not used to view the aquarium. Wrapping drain and return lines in pipe insulation can help maintain the temperature as well!

Reef Stable Recommendation

This is a case of "all of the above". You will need a heater, almost without a doubt. I also find that insulating the sump is a great way to help maintain a more consistant temperature. The only piece that may be questionable is the reef tank chiller. If you have the money, I think that the chiller is a great way to know you won't fall victim to temperature rises. They can also buy you time if your heater gets stuck on. That being said, you have to weigh the price with the reward. In locations that are known to be hot, a chiller is almost a must. In locations like the mid-western states, a chiller is likely added safety but not necessary.

Step 6: Auto Top Off

The sump is an ideal location to do any water top-off because it won't affect any of the living creatures in the reef tank directly. There are three items you will need to place. The first is the sensor. The water level sensor will need to be placed in the same chamber of the sump as the return pump. This is because as water evaporates, the return pump chamber is the section that will see the water level decrease.

The second component is the actual water outlet. This is the tube where the fresh water will be pumped to the sump. You will want this to be higher than the water level to avoid any potential siphons from starting. As for which chamber, there are a few things to consider. You don't want to add fresh water to the chamber with the protein skimmer. The sudden change in salinity can cause the protein skimmer to behave oddly.

You will also want to avoid adding the fresh water to the refuguim. The sudden salinity change could have negative effects on some of the critters that live in that section of the sump. Leaving two areas, the water intake chamber, and the return chamber. The return chamber has the benefit of not affecting any other components, but the negative is that it will but quickly added to the tank. In theory, this should not be a problem though as the amount of fresh water added should be relatively small compared to the volume of the reef tank.

The intake section is seemingly a perfect location. The only thing to consider is controller probes. If you have, or will have probes for a reef controller, they should be part of this first chamber. Meaning the addition of fresh water would quickly cause odd trends to show.

The last thing to decide on is a fresh water reservoir location. Some people like to make this a dedicated section within the sump. Some like to use a nice reservoir to sit next to the reef tank sump. A low cost solution is a 5 gallon bucket or 10 gallon aquarium next to the sump. The decision is really dependent on if it will be visible or if it will be in a stand with closed doors. Additionally, the amount you want to spend plays a role. The cheaper solutions will look worse, but perform just as well.

Reef Stable Recommendation

In terms of placement for the water outlet, I think the answer seems simple. If you have or will have sensors or probes for measuring parameters and connecting to a reef tank controller, you should add the water to the final chamber. Otherwise, you should add it to the intake chamber. As for the reservoir, I use a bucket. My tanks are in the basement so I am able to use a large bucket in a different room. Keeping the reservoir completely out of sight.

As for which ATO you should use, there are a couple popular options. The first is the Neptune ATK. This is a high end auto top-off that comes with a pump as well. If you're looking for high quality and faster setup, this is the ideal option. If you're looking for a lower cost solution that allows for any pump to be connected (not just a PMUP), the the JBJ ATO is what I personally rely on. It has a simple float sensor and an outlet. This lets me use a larger pump to get water to my tank faster.

If you have a reef controller such as the Neptune Apex, you can add optical sensors in addition to the float sensor as a redundant, backup control.

Step 7: Balancing Alkalinity, Calcium, and Magnesium

I won't get deep into dosing Alkalinity, Calcium, and Magnesium because I already have an in-depth article that covers that topic. If you need more information, check it out here:

How to Start Dosing Calcium, Alkalinity and Magnesium in Reef Tanks

As for how the sump comes in to play... When you are balancing alkalinity, calcium, and magnesium in your reef tank, you need somewhere to add these to the tank. It doesn't matter if you are using 2-part supplements, kalkwasser, or a calcium reactor. All of these methods need somewhere that the additives can be added to the tank. The solution is the sump. The big question however is the location in the sump where these can be added.

I'm going to start by saying you want to provide additional alkalinity to a chamber with high flow. This generally rules out the refugium chamber and the intake chamber. If your intake chamber has high flow, it may be a valid location, unless you have probes or sensors in this chamber. The increase in parameters will lead to bad readings if they are added in the same location as the probes.

The locations where I found to have the best flow with no negative effects have been near the output of the protein skimmer, and the return pump chamber. Both of these areas in the reef tank sump have high flow and won't be poorly affected by the raise in levels.

BONUS Step 8: Parameter Monitoring

As a bonus, I will note that many reefers now rely on reef tank controllers to monitor parameters. Namely the Neptune Apex and the Neptune Trident are heavily used for monitoring pH, salinity, temperature, alkalinity, calcium, and magnesium. Some additional testing devices such as the reefbot and mastertronic will allow you to test a wide range of parameters. So, where do you place the intake for these testing and monitoring mechanics? Easy answer is in the intake chamber.

The intake chamber should be free of additives, and free from the auto top off if you are using it for monitoring, as mentioned in the steps above. This will give you the most consistent readings, unaffected by the other sump equipment.

Conclusion

In this article, I have covered the benefits of a variety of options for different filtration types. Additionally, I have discussed where each of these components should be placed within the sump to get the most performance out of it! Though it is best to do this in the beginning, like me, sometimes redesigning the sump after the fact is worth the work to get more out of your filtration and equipment!

Hopefully you found something helpful in this article! If so, please share it with others using the links below!

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Recommended Reading:

• Complete Guide to Saltwater Aquarium Filters
• Saltwater Refugium - What are They and Do I need One?
• Mangroves for Aquarium Nutrient Control
• How to Start Dosing Calcium, Alkalinity and Magnesium in Reef Tanks
• Simple Rules for Picking a Fish Tank Heater

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About the Author

John Krenzer

John is a Software Engineer with a passion for saltwater aquariums, as well as the founder and president of Reef Stable. He started in the aquarium hobby as a child with a 20 gallon freshwater aquarium. His interest in aquarium life grew and in 2008, John set up his first saltwater aquarium.

Today, John maintains an over 300 gallon reef tank system, consisting of a 120g reef and a 210g reef. These large tanks are contained within the same system, sharing a sump as a means to reduce total maintenance and increase total water volume.

John writes articles for the blog as a means to learn about more reef aquarium topics. These articles act as a reference for the readers as well as himself. John updates these articles frequently to provide additional information or make corrections as new information becomes available.

If you would like to request an article, tank tour article, or to collaborate, let me know via the Contact Me Page!

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