This is an idea one “Gardenman” on the Aquarium Co-op Forum came up with. He put the plates and lifts of two undergravel filters into two aquariums. He then covered the plates with two inches of 40 ppi charcoal colored foam. He put an air stone in one of the lifts and a powerhead on the other lift tube. The result were two surprisingly good-looking aquariums.
This will do a great job of biofiltration as the surface area is huge. It is also quite easy and surprisingly cheap to make. It is even cheaper than using gravel, given the current high price of aquarium gravel. This is simply a great idea! This is one of the tanks he did this to:
The plants grow quite well in the foam, putting roots directly into the foam. Note he has two sponge filters in the tank in order to “seed” the bottom foam. He removed the sponge filters after six weeks.
If I were doing this, I would probably use a 30 or 20 ppi Poret foam, but that is hardly a requirement. Because of the large top surface of the foam exposed the flow at any given point is relatively small, which means there is no force drawing the feces into the foam and plugging it up. And I would go with one inch foam.
Some cautions about alternative designs. Some want to add a sizable layer of gravel over the foam. This will compress the foam and make it useless. Others want to add a quarter inch thickness of foam under the plastic plenums. Anything, and I mean ANYTHING, which is placed under the plenums will prevent uniform flow over the surface of any undergravel filter. So never put anything under a plastic plenum.
Some will question why the foam won’t just plug up with brown gunk and stop the flow of water. The answer is that normally in 99% of all aquarium the conditions are such that the decomposition rate of the “brown gunk” is equal to the addition rate.
Now ANY filter can be overloaded. If one has some combination of VERY heavy stocking, heavy feeding, low protein food, poor aeration and/or no good inoculate then one may VERY RARELY plug up a foam undergravel filter. But this is not something for most hobbyists to worry about.
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Would a very light layer of 3mm-5mm gravel compress the foam matten? I have a good amount of 30ppi foam and would like to try this in a lightly planted tank. I have mature filters to seed the foam as well.
In reply to Sammy … a very light layer will be OK.
I decided against the layer of gravel over the foam as per your suggestion. It was a good choice. With 1-1/2″ of 30ppi foam, I made shallow cuts in the foam and inserted java ferns, bucephalandra and bacopa. The roots are tenaciously holding on to the foam. You were right, plants have no problems rooting into foam… no gravel cleaning either. The addition of the internal UV filter behind 1″ of 30ppi foam ( sculpted to a ‘Tiki’ look) is quickly becoming my favorite tank, not to mention, the clearest. My only regret was the flat black background on the tank (I was led to believe the fishes colors would ‘pop’ against the black background) but I will experiment with that.
When I get a canister with static K-1, I’ll move the Tiki to the next tank to seed it and clean it.
Thanks for your help, Dave. Your insight has my tanks cycling and producing in leaps and bounds beyond my hopes.
Next, I’m going to start a Daphnia and neocaridina tank – fresh, live food and something new to enjoy. If you have any pointers on live cultures, I’d love to hear more.
Cheers
I’m currently employing a bottom tank matten filter design with 1.5″ matten filter 30 ppi foam with a thin layer of gravel. Right now there are 2 lift tubes on opposite corners from one another on the back long side of the tank from the undergravel plenum. One lift tube is currently not being used and is closed off with 30 ppi foam. The other has a power head rated 197 g/hr and is running speed. The tank is completely filled with measurements 36″L×18″W×17″H.
My question being can the single power head I have in one of the single corner generate enough lift to distribute flow across the 972 cubic inches of foam. Or would suggest adding another powerhead to the other lifttube?
In reply to Jon … 34 inches is too far for an undergravel. I would add another powerhead.
Can a powerhead like this one:
https://www.amazon.it/dp/B008AYXQEA
(1000L/h) be sufficient for a 100cm long aquarium?
Is it better to place the suction tube in the center or on the side, or does it not matter?
Thanks!
In reply to Stefano I assume you mean to use this with a bottom of tank Matten filter. I would switch to two lift tubes in the back corners and two powerheads rated around 500 L/Hr.
In reply to Dave
Sorry my fault, i mean with a “classic” undergravel filter thanks.
Stefano …. For a “classic” undergravel filter go with two lift tubes and two 500 L/Hr pumps.
I have a 65 gal breeder with 3/4″ 35ppi foam over under gravel. I do have about an inch layer of smooth course gravel over it is because it’s mostly a loach tank. and I don’t want their barbels catch on the foam. I have two HOB power filters as well and wondered what your opinions are about any of this setup and why. Should I remove the foam and increase the gravel? Do you think the HOB filters okay? The tank is 36″ x 18″ x 24″ high. I do vacuum the gravel weekly and clean the HOBs because loaches are larger and do create more waste than average mid level fish. It’s been running a little over 18 months and I have no complains about the set up, but I’m open to any ideas from you..
In reply to Donna …. Sounds like an excellent set up with no recommendations from me.
Hello Dave,
Thank you for this invaluable website, your unbiased info is really refreshing in this age of misinformation.
I have a Juwel 450 vision (my first aquarium) with the original filter installed (Bioflow 8), I have replaced all the media inside it with 30ppi foam which I made sure to cut perfectly.
This gives me 8pcs of 15x15x5cm and if my calculations are correct that gives about 546 cubic inches, which can only handle 1.09 pounds of fish with crystal clear water.
I want to have more fish and more surface area per fish (Angelfish/Discus). My idea is to put a UGF with a 30ppi foam on top.
The UGF plates I have found are 14x7cm, I can fit 72 of them in my aquarium, the total area of them will be 1089 square inches, if I put 5cm thick foam on top of them I will get 2134 cubic inches of 30ppi foam and this will give me the capacity to keep 5,36 pounds of fish with 100square feet per pound of fish so with the 200 that you suggest for Angelfish/Discus the number is 2,68pounds.
Total 3.18 pounds of fish.
Please correct me if I’m wrong anywhere.
My questions are:
1, Does the UGF Bottom of the tank matten filter work if the plates are covered but the foam isn’t all the way to the glass?
2, If not, will covering the sides of the plates change that?
3, If yes, does filling out the spaces around the UGF plates where there is no space for plates (in the bow front) with foam increase the area or should I just fill it with gravel?
Thank you in advance! / Askydra
In reply to askydra………
1, 2, Foam needs to go to the glass or down the sides of the plates
3, fill the bow front with foam or gravel. It will make no difference
Thank you so much for your quick reply.
Another question, if I may, I’m planning to have three 360l/h powerheads in short uplift tubes (aeration will be from spraybar connected to the bioflow filter creating choppy waves and 1 medium sized airstone) is that enough or do I need more powerheads?
In reply to Askydra …………..three powerheads will do the trick nicely.