Penn-Plax Undergravel Aquarium Filter for 40-55 Gallon Tanks – Four 11.25” x 11.25” Plates – Under Gravel System for Clear, Clean Water – Safe for Freshwater and Saltwater Tanks (CFU55)

I've done aquariums for 40 years and have found these very useful. As long as you care and maintain your aquarium I've never had to pull it up and clean it out.

they work great

Great quality product. Easy to use and very functional...Makes using an aquarium plenum a pleasure.

Delivered as described. Quick ship. Fair price for the the quality. Would purchase from again.

👍

Works well and easy to install only kind my boyfriend will use in his tank.

The "filtration" device operates for a very limited amount of time. The concept is excellent - water passing through the aquarium substrate is cleaned mechanically, etc. However, in reality, the aquarium substrate gets covered with silt deposits over time, and this design will no longer be able to perform its primary function. The only way to address this is to siphon the substrate during each aquarium cleaning, which is recommended but does not guarantee the continued operation of the device.

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We bought these to put in our 75 gallon tank so that our fancy goldfish had extra filtration. We already use a canister filter for them but I had an extra air pump from when I got an under gravel added on to my 55 tropical tank (because I'd accidentally ordered 2). I use this same brand in that one, as well!The price is awesome and they work amazingly. Helps keep the water oxygenated and they fit perfectly. Once you get your gravel or substrate in you don't even notice them.Also, these don't make noise: whatever noise you hear comes from your air pump, and if the air is too strong or you have a crappy pump, then yes, they're loud-but do it right, with air line adjustable knobs and a good quality pump and you'll have no problem. The lines were great and they gave plenty with the set up to get it up and running! Will be back to buy another one soon since I'm setting up a 3rd tank soon!

Well made under gravel filter. I used it in a 40 Gallon tank I'm just starting to set up. I used three of the four supplied bases and my tank is 36 inches long. Everything was there taped up. The plastic is perfectly adequate for the job. There is no need to go heavy duty on these parts. They will last decades as is which is more than can be said for the HOB filter variety. Just getting back into the hobby and I learned my lesson well when the HOB filters became the preferred profit makers for filter companies years ago.Once a very popular filter, actually it was considered the best at the time, it is now frowned upon and is no longer considered the best filter to use. This is not because the filter is not great at what it does, its just that the definition of "best" has been refined for modern times. "Best" is now defined by a product that requires regular purchase of filter media to get the "best" profits for companies producing them. They are also "best" at wasting resources and adding to landfills. They are also "best" at unreliability being at about five years or so.So if you want the "best" available today in terms of all those things, don't get this.This filter won't create waste for land fill, won't fail spectacularly, won't require you to keep the filter companies profits afloat, but it will filter your aquarium crystal clear for decades without issues or monthly costs. Just understand how they are meant to be maintained (leave them alone!) and you are good to go.

I bought this for one of my 75 gallons as a test because this item is so inexpensive.So far working great. I have canister filters, sponge, and hang on the backs. For some reason this under gravel filter makes the water look the most clear. I believe benefits bacteria will thrive because of the huge surface area.PROS: very clear water. Handles debris just as effectively as other filters. Air atone works really good. Good for plants as waste is held under gravel for plant roots to maximize on.CONS: have to pretty much dismantle the tank to set it up. Parts seem a little cheaply made, but not too bad, and I must say they are all working fine and haven’t given my any issues.

Good

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.