How to setup mattenfilter sump for superior filtration

  1. bigdreams

    bigdreams Well Known Member Member

    Setting up a mattenfilter in sump

    I finally set up my sump for a freshwater planted tank ( and am very happy with it. It took a lot of research, but in the end, it seems incredibly simple; hard to believe it took so much research to make it a reality. Most sump-related articles and web resources are geared towards salt water aquariums. These sumps can range from simple to overly complicated. I am sharing my setup in case others find it helpful. Please feel free to post questions so I know what topics to expand on.

    First, I assume you have already done some reading and research. For example, you already decided that a sump is a superior filtration method to canister filters. Not going to try to convince you. To me, its a no-brainer. My 29 gallon sump is HUGE compared to a canister filter… case closed. Also, I assume you know that sumps can overflow, and want to take steps to avoid that. I’ll start with the research findings, and will talk logistics/design in future posts. Subscribe to the thread to get updates.

    Here's the big picture overview for all you big picture thinkers out there:

    My filtration goal: super-low maintenance filtration for planted tank. (55-gallon tank) and easier, less stressful water changes for my fish

    Filtration strategy: 29-gallon sump consisting of Poret foam and appropriate pump/flow-rate to create HMF filter in the smp. Koralia circulation pumps in main tank to ensure lateral flow.

    Some background: I had Aquaclear 70 with QuickFilter as the “prefilter” to clean out small debris and keep water crystal clear. It worked, but the QuickFilter clogged after about a week, and had to be replaced weekly. Some may consider this “underfiltered” for a 55 gallon tank, but it worked for me given that my tank was heavily planted. Not sure the filter did much biofiltration, I am pretty confident my plants did most of the biofiltration. Changing out the QuickFilter was messy, and was getting expensive to replace weekly. I want to increase the stocking level so wanted more filtration as well as more water volume. Also, I wanted to lower stress to my fish during water changes; wanted to premix the chemicals, equalize the water temperature, and not have to worry about freaking the fish out during water changes.

    Summary of theory/research findings:

    Filter media.

    After extensive research, I decided that a Hamburg Mattenfilter (HMF) was the way to go. These are basically very large sponge filters with a particular flow rate to optimize bacterial filtration. No need for bioballs, etc. Just a couple of sheets of Poret foam that last forever and can go 12 months between cleanings. There are knockoffs and cheaper options out there, but I choose German engineering over Chinese knockoffs anyday, so I went with the Poret foam from Breeders and hobbyists typically use these foam sheets in the tank itself, either at the end of a tank, or in the corner, as a corner filter, but I didn’t want that. It’s even easier to maintain in the sump, and it won’t make the tank look ugly.

    For the “definitive” reference on mattenfilters, I would check out
    Use Chrome and google will translate it from German to English for you.

    The key issue here is getting a good flow through the filter to achieve the HMF filter effect. Too fast flow, and you won’t get all the benefits of a mattenfilter. Too slow, and you won’t be pushing enough water through the filter to be an effective biofilter. The equation is shown here:
    (I’ll post an example for my sump later).

    Sump plumbing. Drilling the tank wasn’t an option for me (tempered glass in the Aqueon 55 gallon tank). I decided against a DIY PVC overflow due to risk of flooding. I wanted to see the water flowing over the tank wall, and PVC pipe wouldn't let me do that. I instead bought a eShopps 1100 Overflow box, the one with two 1” return lines and clear U-tubes so I can see the water flowing over the tank wall (and any accumulating bubbles, if any). The two return lines were a must for me. I use one as an emergency overflow, as in a Herbie design. For more info, checkout

    Personally, I think a BeanAnimal design is even better in a coast-to-coast weir, but I couldn’t drill the tank for three bulkheads. The eShopps Overflow box had a max of two bulkheads. Stil, two is enough for a Herbie design, which when properly setup is pretty safe and QUIET! I have the sump running now, it is really QUIET, too quiet, actually. I changed the flow so I would occasionally hear some noise… LOL. That way I know that (1) it's working. (2) hasn't flooded my living room yet.

    Here's a picture of the sump while I was testing the flow:


    Two words: lateral flow. more info later (need to dig up my bookmarks and find the good links. Good info on properly flow is surprisingly hard to find on the net, lots of misinformation out there).

    Also, the sump pump isn't the main source of flow in the tank. Use circulation pumps in the main tank to boost flow, and make sure to get the sump pump to hit the properly flow rate to achieve HMF/biological filtration.

    Ok, more info later, feel free to ask questions so I know what to expand on!
  2. TexasDomer

    TexasDomer Fishlore Legend Member

    What size return pump did you use? What size are the pipes going down?
  3. OP

    bigdreams Well Known Member Member

    Q: What pump did you use? what size pipes going down?

    I will share what return pump I used, but keep in mind this works for my setup and needs. Each tank is different, and you will need different pump depending on your setup.

    Short answer:
    • EHEIM Compact+ Pump 2000 (adjustable flow 250-500 gph). It has a 3/4" barbed output, I used 3/4" tubing on that for the return line to the main tank.
    • 1-Inch OD x 3/4-Inch ID tubing to connect the pump to the return U-tube
    • U-Tube with Directional Return (You can buy these on ebay too.)
    • eShopps PF-1000 Overflow box Got mine at on sale
    • 2x 1” Bulkhead fitting with integrated straight 1” hose barb slip inlet x barb outlet (BF1SB) from
    • 1-inch ID (inner diameter) black tubing (to attach to hose barb bulkheads)
    • gate valve (to adjust the flow in the Herbie setup). I used a ball valve, but if I were to do it again I would go for gate valve instead in a heartbeat
    • bought food-grade silicone pads (like the ones sold at Bed Bath and Beyond to place hot pans on) placed under the pump to dampen the vibration.

    Longer, hopefully more helpful/insightful answer:

    First of all, you don't want too strong of a pump because your fish and plants will be knocked around. You also don't want too weak of a pump because your overflow u-tube may break siphon which means it will stop draining your tank, but your pump will keep pumping, so you will have a very large mess on your hands with the tank overflows with water.

    So a few considerations:

    1) What kind of fish you do have? Do they like gentle flow, or do they require stronger flow?

    I have gourami, rasbora, and cardinal tetras (for now). All these prefer gentler flow. So it doesn't make sense for me to get a return pump that will give me 10x turnover. I dialed the sump to full power and they were getting pushed around big time, which only stressed them out so I turned it down. Don't stress your fish out ;)

    2) Don't believe the hype; you don't need a huge return pump for your sump.

    There is no need to go crazy and buy a huge pump to get lots of flow in the tank. You can use circulation pumps and/or powerheads to achieve the in-tank flow you need. The sump pump is meant for filtration. So you can probably do fine with 3-5x turn over. No need to do 10x via your sump like you would do with a hang on back (HOB) filter. For biological filtration to work, the bacteria needs a certain amount of "contact time" with the water. No need to go overboard and undermine your bacteria colony.

    3. Do you want to have a mattenfilter or just want a "traditional" sump?

    In a traditional sump, you have different chambers, divided by baffles which need to be attached to the sump tank using silicone. You need to cut things precisely so they fit, and make sure chambers don't overflow into one another, etc. etc. Seems like a lot of work to me.

    In a mattenfilter sump, you can have sheets of Poret foam work as baffles. No need to install separate glass or acrylic baffles. At 3" thick, they will be lodged in the tank really well, nothing is getting pass them. For freshwater sump, where you don't need all the compartments because you are not running a protein skimmer etc, you can skip all the complexity, buy a couple of 3" Poret foam blocks that are slightly wider (3/4" wider) than your sump tank and be done. I bought mine at and received them within a couple of days.

    In my sump I have a 3" 20ppm Poret foam block followed by a 3" 30ppm Poret foam block. There is no "passthrough" and the surface area is massive - approximately 16" x 12". No microbubbles that I can tell. Any bubbles from the water spilling down from the drain pipes are captured in the first foam block. 3" will give me additional time in between filter cleanings (stretching it out to 8-12 months depending on waste load).

    I decided to approximate the mattenfilter as best as I could to get optimal filtration results for relatively low investment. (No need to buy additional filter media, install baffles etc.). If I ever need to repurpose the 29 gallon tank I can, I didn't wreck it with baffles, etc.

    Ok, tell me about the return pump already!

    Ok, so what return pump and why? Well, I had bought the return pump before I had learned about mattenfilters, so in one sense, "I had to make it work." I wasn't going to buy another pump. Luckily the pump worked out for what I needed to do.

    When designing a mattenfilter sump, you need to take into consideration:
    1) surface area of the mat
    2) flow rate

    because you are aiming to get about 7-10 cm/s flow through the mat. So, first question to answer:

    1) how deep and tall is your sump tank?

    This will determine the surface area (A) of the mat. In my case, I have a 29 gallon tank I was going to use as a sump. That's about 11.5" deep and 16" tall in terms of water volume with no substrate and leaving some wiggle room (~1 inch) so I don't overflow the tank in case the foam blocks get clogged. Remember to measure the inside width of the tank, or you can instead measure the outside glass walls and subtract the thickness of the glass if that's easier for you.

    Surface area A = length * width

    So, converting to centimeters (1 sq inch = 6.4516 cm^2) we get:

    Surface area = 11.5 * 16 * 6.4516 = 1187 square centimeters (cm^2)

    What size is your sump tank? Do a similar calculation to figure out the surface area you are working with.

    Next, figure out the flow rate you need to get 7 to 10 cm/minute flow rate through the foam, or something reasonable close to that range. The equation for flow rate (V) is:


    So, we need to convert units... at an estimated flow rate of 240 gph (see below how I get estimated the actual flow from my return pump), that's equivalent to 15 Liters/minute (240gph * 3.78541 (L/gallon) /60 (min/hour) = 15.14 Liters/minute). So our equation is:

    V = 15.14 * 1000 / 1187 = 12.75 cm/minute

    So a flow rate of 240 gph would be reasonable. A slower rate of 180 gph would give me 9.56 cm/minute, which would be even better but as Dieter says on his website, no need to go bonkers trying to get the "perfect" flow. This is good enough.

    So, now you have your return pump and overflow flow rate requirements.

    I could have used an overflow box that gave me ~300 gph flow. But all the ones rated at that only come with one drain line (which is a no-go for me), and who knows if they really push water out at that speed. I wanted to have two drain lines in my overflow box. The smallest overflow box that I could find with two drains lines was the eShopps PF-1000 Overflow box.

    I highly recommend having two drain lines so you can do a Herbie style overflow. This way you have an emergency drain line in case the main one gets clogged. Also you can tweak the flow so that the drain is silent (as in perfectly silent), which is a big plus, especially as drain lines are notorious for being noisy and make lots of gurgling noises.

    The EShopps 1100 overflow comes with 1" bulkheads for the drain line. It also comes with two 1" u-tubes. I only used one 1" u-tube because I am not using the overflow at its full 1100 gph capacity. (Highest I went during my testing was ~400 gph and the one u-tube was barely keeping up, so I think the 1100 gph rating capacity is a bit optimistic).

    I chose hosing over rigid PVC pipe for ease of installation. Totally up to you how you do it. However, I did learn something. 1" tubing does not equal the flow rate of 1" PVC pipe. (Sorry , I'm using hosing and tubing interchangeably, probably shouldn't). Rigid PVC pipe is nominally measured by the inner diameter, while it was super confusing how the tubing was being measured (inner or outer diameter)... best to know both OD/ID to make sure you aren't buying the wrong size.

    I got 1" black tubing from Fosters and Smith (they had a sale), and that attached easily to 1" barbed fitting. I used stainless steel metal clamps to secure the hoses in place. In my 1" slip x 1" barbed fitting bulkhead, the barbed fitting side is narrower than the slip side to accommodate the barbs. So, there is loss of flow rate there. Something to keep in mind. I think for practical purposes it reduces to about 3/4" inner diameter. In my case that was OK because my pump has a 3/4" barbed connector outflow. For my pump, I used 1-Inch OD x 3/4-Inch ID tubing. So in essence my return flow seems to match my pump because the pump itself has 3/4" barbed output. These are the little details that you learn along the way... hopefully these unexpected details don't derail your project.

    I used the EHEIM Compact+ Pump 2000, bought it on Amazon for about $80. It has an adjustable flow of 250~500 gph. Remember, these rates are at "zero head", i.e., with nothing attached to it. I'm lifting the water about 3 feet, so I am probably getting about 80% of the rated flow. (Check the pump's head chart to know how the head drops off with additional height. If rated at 7 feet, the flow rate is 0 gph at 7 feet!).

    I dialed the flow knob down to about 20%... (20% between the minimum and maximum flow) so I'm guessing that's about (500-250)*0.2+250 = 300 gph at zero head. Add in 3' of vertical lift, I'm estimating no more than (300*0.8) = 240 gph, probably closer to 180-200 gph. The only way to really know for sure is to put a 5 gallon bucket at same height as your tank and measure how long it takes to fill the bucket. I have to admit I was too lazy to do that, and was OK with my estimates.

    I have 40 gallons of water in the 55 gallon tank once substrate and gap at the top of the tank for air are taken into account. (That itself was an eye-opener for me, that my tank had less than 3/4 of the water it is supposedly has), plus another of 20 gallons of water in the sump, giving me a total of 60 gallons of water volume. At 240 gph, I have 4x turnover (with no pass through).

    Now in terms of the matten filter, at 240 gph, with 1187 square centimeters of foam surface area, that gives me a flow rate of about ~13 centimeters/minute. Higher than the "ideal" rate of 10 cm/min, but still reasonable and very effective. (Something unreasonable would be 50 or 100 cm/min which would be insanely high). So I should be getting the benefits of the mattenfilter this way.

    Tell me about the return line already!!

    In terms of the return pump, I connected the 3/4 inch hose to the output of the Eheim 2000, that connects to a U- Tube with Directional Return. It's basically a rigid plastic pipe w/ a built in u-turn and adjustable water spigot thing that going into the tank. It's a single piece of plastic with smooth turning angles so flow rate loss is minimized compared to building something similar with PVC elbows and fittings. It has attachments for either 3/4" or 1" hose. The nozzle is rectangular and forces a strong stream of water through it. I removed it and have the return pump water directly into the tank (towards the bottom of tank). (See section on lateral flow as to way I think this is better) I raised the return by putting Lego blocks on the tank wall and resting the u-tube on it, so now the return is only 1/2 inch below the water's surface. In case of the pump shutting off, only 2 gallons of water will drain back into the sump! Pretty good, and no need for a ball valve on the return line which would have reduced the flow!

    The return line is located in the back left corner and pumps water directly down towards the substrate. This isn't ideal, but was the best position I could come up with. In this way, there is flow to the bottom of the tank. I put a piece of foam on the substrate so that the water won't blow sand away. It is helping keep that part of the tank from becoming a crater... which is especially important to me since I have soil under the substrate. The water hits the substrate then spreads across the substrate, bringing nutrients to my plants. Water will rise up and drain into the weir on the right side of the tank. As you can imagine the flow in the front right corner is minimal, if not close to zero. Yet even so the water is crystal clear right now. To boost overall tank circulation, I have a Koralia pump located in the front right corner that I run on a timer and that helps pick up flow very noticeably, eliminating the dead spot in the front of the tank. The position helps create a gyre, but it's not optimal. I have some ideas on how to further improve things, but given how my stem plants are going like crazy right now, and how crystal clear the water is, without polishing pads, I'm not complaining. I have the circulation pump run during the day, and turns off at night, giving my fish some very tranquil water to sleep in.

    I have a few additional future enhancements to my sump set up in mind:

    • adding a float switch to shut off the return pump if the water level in the pump reaches the rim of the tank, also sound an buzzer or alarm if water level is too high
    • repositioning the return to create a "gyre" and promote stronger lateral flow

    Ok, hopefully that was helpful to people.