How I'm Supercharging My Fx4/fx6 Filters With Poret Foam

I recently acquired a new 225 gallon aquarium to set up a fancy goldfish tank. This is quite a bit bigger than the 130-gallon I *thought* I was going to set up, but it was a killer deal and I just couldn't pass up the opportunity.

Due to budget constraints, I have two canister filters to work with right now: a Fluval FX4 and an FX6. The previous owner was successfully using a single FX6 with an arowana, gar, and super red oscar. But I plan to stock this tank with 10+ fancy gold fish. So even combined, this is stretching it a bit thin as far as filtration goes. This is why I will be "supercharging" both of these filters to get as much out of them as I can.

I've been looking into how to set up a complete aquarium cycle (with both aerobic and anaerobic bacteria) that, once established, should drastically cut down on both water changes and filter maintenance. I thought I would use this post to boil down what I've learned from all of my research and outline how I plan to accomplish it.

The majority of my research comes back to two primary sources: Pondguru (on Youtube) and Stephen from Swiss Tropicals. Both of these sources have developed strategies to achieve a complete cycle with aerobic and anaerobic bacteria to take ammonia --> nitrite --> nitrate --> nitrogen.

Pondguru does this by layering standard pond filter foam pads of incremental porosities for mechanical filtration, followed by his own Biohome media for biological filtration. He has many videos, but the one that really goes in depth and explains everything you need to know is

. Swiss Tropicals, on the other hand, uses Poret foam in a Hamburg Matten Filter (check out this

from King of DIY if you are unfamiliar with what that is) for all-in-one filtration. According to the manufacturer, Poret has more surface area to house beneficial bacteria than most other kinds of biological media and can support both aerobic AND anaerobic bacteria for a variety of reasons I won't detail here. Perhaps more importantly, the foam does not compress or disintegrate over time, giving it an exponentially longer lifespan than typical filter foams. You are welcome to check out this

for more details/explanations about how and why it works.

I ordered Poret foam from Swiss Tropicals (as they are the sole distributor for Poret in North America.) Stephen, the owner, was awesome and answered all my questions and even saved me some time and headache by cutting the foam down to the specifications required for my canister filters.



ORDERING THE FOAM:
The following was more than enough to fill BOTH my FX4 and FX6 canisters. After shipping, it cost $88. So not the cheapest method in the short run, but I hope it will pay off in the long run.

1- 26x19.5" sheet of 10 PPI foam (1.5" thick). Cut into ten strips of 14x3.25" each* (see note below)
1- 19x13" sheet of 20 PPI foam (1.5" thick) cut into four 6.5" squares
1- 19x13" sheet of 30 PPI foam (1.5" thick) cut into four 6.5" squares
1- Gallon of 45 PPI Poret aqua cubes (1" cubes)

*(NOTE: I had my 10 ppI strips cut to 14x3", but found that this left small gaps between the media baskets where water might be able to bypass the 10 ppI foam. Luckily, my package included the leftover 10 ppI foam, so I was able to cut out some thin strips and stuff them in to fill up those gaps.)



The dimensions and setup on both canisters are identical except the FX6 has an extra media basket. I'll explain what I did with that in just a minute.


CUTTING THE FOAM:
Even with Stephen precutting the foam to my specifications, there were a couple of modifications I needed to make before installing.

1. Cut the corners off of each 6.5" square. You do not need to make them perfectly round--just take off enough to make it easier to stuff them down into the baskets without leaving any gaps on the sides.



2. To make it easier to install the 10 ppI foam into the outer baskets, fold the strip of foam in half and use scissors or a sharp knife to slice a vertical slit in one side. (This will help get it past the "hump" created by the intake/outake tubes)





INSTALLING THE FOAM:




1. Stuff one 10 ppI foam strip into the outer chamber of each media basket (two per basket). For an FX6, you will need 6 strips. For an FX4, you will only need 4.

(TIP: Technically the available space here is 1.25", but Poret comes in 1" or 1.5" increments. I opted to go with 1.5 and I'm glad I did. There is enough give in the foam to squish it in, and that means I squeezed that much extra filtration into the same space.)

Start in the middle by spreading the slit you cut around the "hump" for the intake/outake tubes, then continue out. It will take some manipulating to get the foam all the way to the bottom and then smoothed out.

2. (FX6 only) Stuff as many of the 45 ppI Aqua Cubes into the media tray as you can. The smallest amount of cubes I could order was 1 gallon, which was about twice as much as I could fit. (I did not use any Aqua Cubes in my FX4.)



(NOTE: I am not sure if the aqua cubes have some kind of advantage over flat layers of 45 ppI foam. I got them based on Stephen's recommendation for a canister filter setup and--since it also happened to be cheaper than buying a flat piece of foam--I didn't really question him about it.)

3. Stuff two 1.5" layers of 30 ppi foam into the center chamber of one of the media basket. This will be your MIDDLE basket on the FX6 or your BOTTOM basket on the FX4.

4. Stuff two 1.5" layers of 20 ppi foam into the center of one media basket, one piece of foam at a time. This will be your TOP basket in either the FX4 and the FX6.


WHY I DID IT THIS WAY:

Both the FX4 and FX6 are designed the same way. Water first flows through the outer chambers that wrap around the outside entire canister. It then flows through the center chambers from top to bottom.



This means the foam porosity needs to get progressively finer/higher as you move in and then down into the canister. With this set up, the water flows through 10 ppI --> 20 ppI --> 30 ppI --> 45 ppI (FX6 only) to filter out progressively smaller and smaller particles. Beneficial bacteria will colonize throughout all of the layers of foam, which means that mechanical and biological filtration will occur simultaneously.

IF you were to move right into a higher porosity foam, you'll still get your BB, but the foam will clog much sooner and the canisters will need to be cleaned much more frequently. This wouldn't impact aerobic bacteria and the first half of the nitrogen cycle, but it is not ideal for anaerobic bacteria. This kind of BB takes months in low-oxygen environments to colonize, so frequent disturbances may prevent you from establishing the second half of the cycle (where nitrates get broken down into nitrogen) at all.

I would NOT recommend using chemical filtration, such as carbon, in your canister if you're doing this set up. Chemical filtration would need to placed AFTER all of the biological filtration, which means putting it at the bottom of the bottom media tray. This means: A) It will take up valuable space that would be better used going to your biological filtration. And, B) Since it only lasts a couple of weeks to maybe a month before it would need to be removed and replaced, you would constantly be opening up the canister and pulling out the foam in order to get to it.


Anyway, I'll post periodic updates once I get the tank filled and begin cycling to let you know how it goes. Anyone else tried this or something like it before?

 

Excellent write-up. I like your logic and will be very interested to hear if you get denitrification from the foam. Given the massive amount you have and the relatively long path the water takes through the filter, it could well have low enough oxygen toward the end that the bacteria will convert the nitrates. Knowing that this works for nitrates would be huge.

I stumbled on the Aqua Cubes while roaming the Swiss Tropicals site. When I looked at the price I immediately wondered why anyone would use "pot scrubbies" in a filter when you can get high quality foam cubes for close to the same price, if not for less. The mixed cubes are even cheaper than the high density cubes you got. At $6/gallon they have to be in line price-wise with scrubbies and obviously have vastly more surface area.

Do you intend to use pre-filters on the canister intakes? I'm sure they'd go a long way toward avoiding the need to open and clean the canisters.

Did you give any thought to combining one of these filters with something like a corner matten filter? That would act like a massive pre-filter as well as providing loads more space for beneficial bacteria. At the very least it should extend the filtering capacity of the canisters.

 

I was just about to post something unrelated about filtration and saw your post. Very good write up. If I used canister filters (which I don't because they are scary to me ((I've already flooded my house once))) I would do the same thing!

 

I am big on sponges and also use porets from Swiss Tropical .
All the other fancy stuff is just that ..Fancy....
Hope this all works out for you .I am not a canister fan or user but when you are ready for a sump your sponges will still work ,You might even be able to fit more !
Look forward to pics of the tank with goldies !

 

Hello Dray...

Actually, you don't need high end, expensive filtration. I have a 300 gallon tank and have no mechanical filtration. I just have a lava rock substrate base, an air stone and perform large, regular water changes. Include floating plants to steady the water chemistry and you're good. Remember, the large, regular water changes are critical for a healthy tank.

Old

 

Dray , excellent write-up!

Very thorough and meticulous, plus the pics/drawings are great. Well done !

Please post updates, especially when it's time to clean them.

I was thinking the same thing that JayH asked about using a pre-filter.

The next time you crack them open for a cleaning, consider what I did to our FX4.

I placed an ATI Hydro Max III pre-filter on our FX4 and it works well.




ATI's are modular, they can be stacked and will accept their larger sponges as well.

I did another mod by trying to utilize some unused void spaces in the bottom of the canister. I placed the included Bio-Max around the outer ring where the water enters and then travels back upward. I got that idea from Pondguru, for large muck to collect there.

I also put a block of foam sponge to act like a dam in front of the impeller assembly intake and placed cycled Pond Matrix behind it.

That area would also be a good place to put a bag of chemical media like Purigen or Chemi-Pure.




The Poret foams you used is top notch.

I discovered the Swiss Tropicals website last year, and have always been very interested in setting up a corner mattenfilter or using their Poret in a future sump build.

 

Do you intend to use pre-filters on the canister intakes? I'm sure they'd go a long way toward avoiding the need to open and clean the canisters.

Did you give any thought to combining one of these filters with something like a corner matten filter? That would act like a massive pre-filter as well as providing loads more space for beneficial bacteria. At the very least it should extend the filtering capacity of the canisters.

The tank has two built in corner overflow weirs, so there is definitely some space and opportunity to play with prefiltration. For now, I will cut up some layers of the leftover 10 ppI foam and fit them into the weirs before the intake.

The tank is 30" tall, so a Mattenfilter might not be the best choice. There may be space in the weirs to fit cube/tower filters with airline-powered jet lifters in the future though.

I discoved the Swiss Tropicals website last year, and have always been very interested in setting up a corner mattenfilter or using their Poret in a future sump build.

I am installing two corner mattenfilters in a 55-gallon aquarium for my classroom tomorrow

I'm using a mattenfilter kit from ST with two large jet lifters and 3" thick 30 ppI foam. I cut the foam in half and will stuff them behind some acrylic weirs I put together to hide the foam. In hindsight, I don't think it's going to really hide much, but it will at least hold them in place.

 

That will be an awesome tank for a classroom!

You won't have to clean it until winter break, if not longer.

Please post pics when it's up and running.

 

The tank is 30" tall, so a Mattenfilter might not be the best choice.

I think a corner Matten filter would be okay at that height. The one in my 20L is only 12" tall, but given how snug the fit is I really don't think the extra height would make a difference. I know you have weirs in this tank so a corner Matten filter wouldn't make sense. Just commenting on whether the height would be an issue.

Are the weirs drilled or just there as surface overflows where you can put the canister intakes? If you could put some coarse foam in there they'd likely make very good pre-filters.

 

Are the weirs drilled or just there as surface overflows where you can put the canister intakes? If you could put some coarse foam in there they'd likely make very good pre-filters.

Surface overflows. That is exactly what I was thinking.

 

(NOTE: I am not sure if the aqua cubes have some kind of advantage over flat layers of 45 ppI foam. I got them based on Stephen's recommendation for a canister filter setup and--since it also happened to be cheaper than buying a flat piece of foam--I didn't really question him about it.)

This was mulling around in the back of my mind and I think I have an answer that makes some sense. The rest of the foam is doing mechanical filtration and the nitrification portion of the biological filtration. The aI'm for the cubes is denitrification. This needs at least pockets of low flow of low oxygen water.

Since water seeks the path of least resistance, it will mostly flow through the gaps between the cubes. Some will find its way into the cubes, but only a fraction of the total water flowing through the filter. That making its way well into the interior of the cubes should be moving very slowly. The aerobic bacteria on the outside of the cubes should have further depleted the oxygen so whatever makes it to the interior of the cube should be low oxygen and low flow, exactly what will promote denitrification.

Flat layers of foam would have even flow throughout and not be especially supportive of denitrifying bacteria. The bypass flow around the cubes sounds like it would be something to be avoided, but in this case I think it's highly desired.

This is all just speculation, but I think it holds up in theory. I'm not at all sure how much of the O2 will be depleted by the aerobic bacteria, though the inside of the cubes certainly seem the place most likely to provide the environment needed for denitrification. If it works at all, that's where it would happen.

 

Update:

I scaped the tank with pool filter sand, beach rocks, grape wood, and green foxtail and used Fitz Pro Aquatics Ammonium Chloride to perform a fishless cycle. I've now added four golden dojo loaches. I have 5 fancy goldfish (a mix of ryukin and orandas) that should be arriving on Tuesday.

I'm still looking for a fun pleco (like a gold nugget, a leopard, or a clown) and some additional fantails.

Here's the result so far:

 

Great looking tank!

I like the simplistic approach to the scape.

Where was the wood sourced from ?

 

Great looking tank!

I like the simplistic approach to the scape.

Where was the wood sourced from ?

I got them from The Love Aquarium in Escondido, but not sure where they acquired from. They had a huge selection, though.

 

Interesting.
Now I feel that I set up my outside foams wrong.
When I rebuild the filter I will stack from big to small on the outside. Right now it is large and medium on each level.
The center of all levels is vermiculite that I drew down in a vacuum chamber full of prefilter rinsings. I think I will stick with this for center as it is affordable and better than sintered hydroponic clay.

 

How is vermiculite better? I would think it would make a horrible media due to the extremely light weight and the friability. I'd think after a fairly short time you'd have tiny bits of vermiculite all over the tank.

Do you have any data on biologically active surface area for vermiculite? It's certainly a lot cheaper than sintered glass but I have serious doubts about how well it will work as media. I've seen what Biohome Ultimate looks like after a year under a waterfall. Given how vastly more friable the vermiculite is, I can't imagine it would last more than a week or two under similar circumstances.

I think I'd be more inclined to go with perlite for bio media than vermiculite if I was shopping the garden section, though I must admit I don't know if there is anything in perlite that would be harmful to the livestock.

 

The friability was originally a concern but since it will be held in place in an FX6 it will not get the chance to tumble and crumble. Do to porosity I wanted to do this for a long time but everything in nurseries looked like it would just blast out of the filter. FX6s do not ship with anything close to a reasonable amount of media so you have to make plans.
I use #8 vermiculite which I found on amazon. The 1"+ chunks go nowhere, they stay where I put them. I would never consider the small garden store stuff.
For me vermiculite is better primarily because it is affordable. Biohome costs gold/cocaine money per oz. 4 cubic feet of vermiculite is 30$? I have a lifetime supply for 30$
Breaking both open you get more surface area out of vermiculite compared fo sintered hydroponic clay. So I have 3 worthless huge bags of sintered clay(I was angry with Amazon and know how shipping costs work, so I bought the max they would allow)... Time to make a PVC strawberry garden in that empty room I guess.

Another thing of note is when you draw it down in your vacuum chamber the dust and debris ends on the bottom of the chamber and not in your tank. You take your vermiculite from the bottom as it is saturated. Floaters get more dumped on them and get drawn down again.

In the future I want to do a 6 gal vermiculite pail with a big showerhead top fed by a large pump pushing through a sunsun prefilter.

It would be very interesting to age in different media on an FX6 and then test it against an nitrated/nitrite garbage can of water. For aging/maturing would just bubbling it in a pail of prefilter rinsings do it? How long, a month?

 

I guess I'm just not seeing where vermiculite would have such huge porosity. I get that it would be better than a solid material of the same volume, but the layers seem non-porous. And they obviously have to be connected at some point or they'd fall apart. So it's not clear that water would circulate through the individual pieces of media.

I'd also think without the vacuum chamber it would take a long time for all the air to work out. In other words, it might work okay for people who have to proper tools, but a non-collapsing vacuum chamber is not something you're likely to find in the average home. I could do a quart at a time, maybe a gallon if I could fine the right container, but I'm weird in that I have a vacuum pistol and some little rubber band-aids that allow me to pull a vacuum on canning jars. I guess people with Food Savers could maybe do it, but, again, a bit of a fringe product.

Okay, I found something that said the gas adsorption surface area of the vermiculite they tested was 0.52 m^2/g. I have no idea if this was garden variety vermiculite or some special kind. This test was not meant for testing use as a biological medium so there was nothing indicating how much of that area would be biologically active. As was learned from the research done by Seachem on Matrix, there can be a very large difference between total surface area measured by gas adsorption and biologically active surface area. (Only ~45% of Matrix total surface area is biologically active.) If we assume the total surface area of the vermiculite is biologically active, that would make vermiculite about twice as good as Substrat Pro and about half as good as Matrix, both for a small fraction of the price if buying in bulk. But that's a very big assumption about the surface area.

I couldn't find #8 vermiculite on Amazon. I've never seen vermiculite in 1" cubes. That's huge. Depending on how water flows through the vermiculite that could make for a very interesting medium. Wouldn't want to use it in a moving bed but for situations where it's contained it could be quite good.

 

Yeah I wouldn't use it without a vacuum chamber. a vacuum chamber + pump + perlite #8 costs less than filling an FX6 with biohome though.
The amount of time it takes for sintered clay to saturate with out an VC also takes a long time. I suspect this is why they tell you to never let it dry out.
For surface area all you have to do is examine a piece or to be extra sure run a chisel through one like you would sintered clay.
Doh, I have been using the wrong word. is what I'm using.
So perlite not vermiculite.
This is embarrassing. Perlite #8. I'm so sorry.
Now I should go correct some posts.

The VC is also needed to open internal surface area by bursting the sealed walls/chambers.

you can also use the VC to make super dense cheese cakes and such. So it isn't just a fish expense.

 

Yeah I wouldn't use it without a vacuum chamber. a vacuum chamber + pump + perlite #8 costs less than filling an FX6 with biohome though.
The amount of time it takes for sintered clay to saturate with out an VC also takes a long time. I suspect this is why they tell you to never let it dry out.

Biohome is expensive. Absolutely no argument on that. I'm not sure if your saturation comment was meant to apply to Biohome, and I'm also not sure this would count as "saturation", but if you just touch a dry piece of Biohome to water it will wick the water to the top of the Biohome within a couple seconds. I've not broken a piece in two afterwards to see if the center is wet as well, but the outside certainly has impressive capillary action, which I think speaks to how small yet open the passages are. I'm fairly certain it would saturate within moments of being submerged.

Doh, I have been using the wrong word. is what I'm using.
So perlite not vermiculite.
This is embarrassing. Perlite #8. I'm so sorry.

Not a problem. I used to get them confused too. I've now mixed enough of each into potting soil that the names are well ingrained.

The VC is also needed to open internal surface area by bursting the sealed walls/chambers.

Ah, okay, I suggested the same thing in the other thread where this came up. I'd be interested to see if that actually worked.

you can also use the VC to make super dense cheese cakes and such. So it isn't just a fish expense.

Can't say that super dense cheese cake has ever been a personal goal, but I'll keep it in mind. I have a pistol grip small vacuum pump that I can use to pull a vacuum on canning jars. I've used it a couple times when making flavor extracts to speed up the penetration of the solvent into the material. You should see the bubbles coming out of a stick of cinnamon. Sadly, in that instance, I don't think it made much difference in the final product. Hopefully it will work better with the perlite.

 

The thing that I have always questioned about things like biohome is how much flow through the media is there after the capillary action saturates it?
My advanced fluid dynamics classes in college do not lead me to think there is much at all due to surface drag (and other drags that are not thermal/cooling). Same for my perlite, hydroponic balls, and if I ever do salt, cuttlefish bone (I worry the calcium might run too high in a tank not supporting corals, so I haven't tried in fresh).
So then I then I wonder about sand filters and moving bed where all of their surface is exposed to the flow all the time and wonder how they compare.

I really just need to stop being lazy and do a few months of garbage can testing.

My VC busts those walls great in perlite. the floaters all become sinkers.

 

The thing that I have always questioned about things like biohome is how much flow through the media is there after the capillary action saturates it?

Biohome is designed NOT to have a lot of flow in the interior of the media. Given that it's virtually impossible to arrange it into a solid block, most of the water will simply flow over the exterior. You'll get aerobic bacteria setting up shop on the outside and probably a short ways into the interior, but then the flow should slow to just a bare trickle. This is by design.

That slow flow means the aerobic bacteria toward the outside will nearly deplete the oxygen from the water that moves deeper into the interior. This sets up zones of extremely low oxygen where the BB will change over to getting their oxygen from the nitrates, leaving behind just harmless nitrogen gas that eventually escapes to the atmosphere. This very slow flow through the interior is essential to removing the nitrates from the water.

If you're using Biohome you want the nitrification portion of the full nitrogen cycle to happen elsewhere, preferably in the several layers of foam you have filtering out all the muck before the water gets to the Biohome. You'll get some nitrification from the Biohome, but that's not it's primary purpose. It's there to deal with the nitrates created in the first two steps of the nitrogen cycle.