Penn-Plax Undergravel Aquarium Filter For 40-55 Gallon Tanks

The product description was accurate. There was a cross reference at the bottom of the page that gave the dimensions of the entire tank, and the dimensions of the glass top which allows for the black plastic frame surrounding the top. When I received the box, one end of the box was smashed. I picked up the box expecting to hear crumbling glass sounds, but to my surprise I did not hear anything. I brought the box into the house and opened the box carefully. The inside of the box was filled with thick packing foam around the sides and numerous layers of bubble wrap tightly bound around the glass. Lots of tape around the bubble wrap kept it very secure inside. I cut off all of the wrap and all of the glass pieces were entirely intact with nothing broken. There were 2 grip handles to peal & stick on the front of the cover. The cover fit my tank perfectly. The quality was 100%. I am very happy with this product and highly recommend it to others. Just be sure to order the size based on the outer dimensions of the tank.

Ich habe mir zwei Packungen bestellt, entsprechend der Aquariengröße zugeschnitten und bin sehr zufrieden. Das Aquarium läuft gut und ist gepflegt wie nie zuvor. Verwende zusätzlich einen Aquarieninnenfilter.
Allerdings: Die Filterkartuschen sollten angeblich alle 2 Wochen getauscht werden. Aber wtf kann man die kaufen??? Von Amazon werden sie nicht an meine Wohnadresse geliefert und wären außerdem teurer als das Gesamtset!!! Scherz oder???
Fazit: Gutes Produkt aber trotzdem überlegen, wie es dann weitergeht …

I’ve had aquariums since the mid 80’s, and at that time the UGF was king. I still think the UGF is far superior to todays HOB and canisters for many reasons and a pain for others.
The reasons I like UGF over HOB or canisters: Nothing matches the filtering capacity of your entire aquariums bottom for mechanical filtering, and as the void under the gravel is where the good bacteria live, you’d be heard pressed to find any other type with the surface area of the UGF for bio-filtering too.
The carbon filter at the top are cheep, easy to replace and if your so inclined, can be replaced for a power head or even opened up for replacing with new carbon (not intended to be used as such, but were all tinkerers here, right?)
What I dislike about UGF: Over time the bottom can, theoretically, become backed-up with waste. If you overfeed or don’t have plants which can consume some of this, it can back-up quicker. However, a gravel vac can remove most of this while doing water changes and in my experience, I’ve gone many years before I’ve needed to remove the UGF, usually I only remove it and clean when I get tired of the tank set up and wish to redo the tank…. and even then, I do it not because it’s needed, but because I’m in there already. This is maybe not a dislike, but as it’s not easy to do, I list it under dislikes.
Over time the tubes usually discolor, become dirty or the like, so over time they will need to be pulled out and cleaned. This isn’t hard to do, but it a bit more involved than cleaning a HOB, but is mostly for athstetics, unless the tubes got too dirty and cause a blockade after years of use.
The final item is by far the biggest and only real dislike I have for them, and should serve as a warning for others, with a fix at the end. If you have a tank where the fish breed, the eggs can get pulled into the gravel and wind up at the bottom of the tank, under the gravel. The eggs hatch and now you’ve got fry swimming under the gravel, had this happen to me. As designed, there is no way for those fry to get out of the system, as the gravel is overhead (can’t borrow through that), and the path to the tubes is blocked off even if they could somehow get through the carbon filter (they cant). So this was the reason I stopped using them many years ago. Was the only reason I stopped using them. Now, to fix this…… The plates each come with 2 spots to put tubes in, most likely you will not use or need all of those spots. Each plate is connected below (when knock outs are removed), so fry can swim between them, simply cut one of the unused riser tubes sections out and insert a use in it’s place as an escape. I used some tubes I had laying around to do this, but I leave the top capped as to not create other issues. If I see fry swim up the tube (which they will), simply open it and let them out. While this is an issue, it’s kind of a double edge issue…. bed they get trapped, but as they are trapped with nutrients below they are not food for others….. have had more than a dozen live down there before and go one to reproduce themselves. How many I lost before this fix… I don’t know.
On to the 3 star ratting. This is a reflection on Penn Plax build quality and changes.
The “old school” design (brown plates vs blue) were made of a very ridged plastic, This was a bit brittle but posed no issues after they base was installed. These new blue plates are about 3 steps backward.
Since they are not ridged, they sag from the weight of the gravel on them and even have give from just the riser tubes installed…. 2 issues the older design, which I still have, does not suffer from. Only time will tell if this leads to more than just crooked looking tubes after it’s installed, but the fact the tubes are crooked for some might be enough to avoid/return this…. I almost did, but I have plants to cover it and added rock under it to help stiffen it up.
The second star was removed as the riser tubes are not as long as they should be or once were.
I have a 49 gallon bow front, on all my old UGF’s the tubes rise high enough to bring the top of the heads just out of the water a bit, making it perfect to filter and reduce the gurgling noise. This new design leaves the tubes 2+ inches below the surface while fully extended and as such you get the bubbling/gurgling noise.
I do love UGF’s, but I do not know that I could recommend these over the other brands out there now-a-days. In the past, it was Penn Plax hands down, but with these 2 issues, I feel I will try another brand when I set up another tank if these are not fixed before that time.
Hope this helps anyone looking for an UGF.

Back in the 80`s & 90`s, i used to keep fish, but had a break from it till 3 years ago, when i purchased my current setup. Back then, pretty much the only filter system around, was undergravel filters and they always worked great. Nowadays though, with modern systems, undergravel filters sort of died out, or so i thought. I have an Ocellaris 1400UV canister on my tank, which i have to say, does an amazing job, but because i`ve now had the tank 3 years, i decided to do a complete clean out of the tank and i have to say, i was blown away by how much muck was in this tank, especially in the gravel. One of the biggest causes of it, was the volcanic substrate i`d put in the tank when it was first setup, as it worked it`s way through the gravel, it had literally turned into lumps of mud and then along with all the other muck, well, you can imagine. So, after coming across these undergravel filters and the fact you could still buy one, i decided to fit this one to my take, because lets face it, you can`t have enough filtering. It all went together great and the only thing i had to do, was trim about 20mm off the width, because it was slightly wider than the tank (front to back). The kit comes with everything you need, even the air stones, all you need to buy, is the pipework and the air-pump. So far, it`s working great, but it has only been a few days. I`ve uploaded a video to show it working. The tank looks a little yellow/orange, because at the time, my full spectrum light was going into sunset mode, but you can see what you need to 🙂 Great kit, easy to fit and great value as well, certainly worth fitting.

Perfect fit in my 55 gal. tank. Couldn’t find this type at the store. Most if not all I saw was complete crap designed by someone with zero clue what a fish tank is.
Permanent, cuts way down on chemicals and smell coming out of the gravel. You can also pull the grossness out of the grids while suctioning out water

I had more trouble assembling it than I expected, especially removing the tabs between plates. That is a good thing, because it means the plastic is tough and durable, not hard and brittle.

I took one star away because the plates don’t stay attached very well, so I drilled small holes and used cable ties to hold them together firmly.
Altogether very good!