19.2.2020

This is a long term review as this exact filter was bought April 2018 and used yearly/monthly/weekly/daily/hourly/minute by minute ever since !I've been a Fluval customer for decades, I've had a number of their filters with dozens upon dozens of tanks over the years and what keeps on me being loyal?1. Quality2. Dependable3. Does it's job day in day outI've been in the hobby for decades and have kept salt/fresh bare bottom/planted and everything in between. I've given speeches, helped 100's of people in this hobby and in all that time and experience you can easily weed out poor manufacturers and you quickly gravitate to manufacturers who provide that dependability that is DEMANDED with the aquarium hobby.In all my years I've never had any Fluval filter quit working for me.Personally I'm in the underwater/submerged phase of tank keeping I guess you can say. I've converted all my main tanks with the Fluval U series and three tanks have this same Fluval U3 for a few different reasons, most importantly is for it's silent operation. I have a couple tanks in bedrooms and the old HOB Hang On Back type filters tend to let the water drop too far as to create that waterfall noise. Some may like that noise but I call it noise for a reason. With the underwater series such as this U3 there is zero and I mean ZERO noise from the filter.No fish stories here so I included the three U3 series filters as proof.For the filter itself, you can adjust the outflow in various regards, the filter unit itself clips into a holder which is suction cupped to the aquarium glass wall and opening the top door to change filter material is quick and painless. If the filter does not sit well in the filter cage something is just blocking it a tad, most likely it is the power cord so just rerun the cord past the clips on the back of the filter and your good to go again.TIP ► When doing any tank filter maintenance I strongly suggest to turn it off first. When I do filter maintenance I completely remove the entire filter into a bucket and then open it to change out filter pads. I do this because if you change filter pads in the tank and plug the filter back in, debris will shoot out of the filter like a hurricane. Change out filter pads in a bucket, rinse the filter itself in some water and you've minimized the debris hurricane.TIP ► There are 5 basic areas within the filter.1. The ceramic media. Never clean this part...leave it nice and dirty. Caked in debris isn't needed but if there is just remove that debris, don't try to 'wash' the ceramic rings. They also don't need to be replaced. If they are turning into powder, sure but in all my years I've never had to replace ANY ceramic media !2. On either side of the filter there is a course then fine area. The course is the sponge and material is first trapped into this. When you do your REGULAR maintenance squeeze this out in water only. You don't need to replace this as the sponge will last for many, many, many years.3. The final stage is a bad that 'polishes' the water and this includes activated carbon within that filter pad. In my tanks I don't run activated carbon and I caution against using that in most cases actually, so when my filter pad gets dirty I only squeeze this filter pad out in water and I don't replace it. The filter material's integrity against the plastic filter pad cage will last for years and years. People replace their filter material much too frequently.Sorry aquarium filter manufacturers... But they all tend to advocate replacing the filter material wayyyyy to frequently. Replacing filter materials is a huge profit maker for manufacturers.TIP ► In doing filter maintenance when a filter sponge or pad needs to be rinsed some people state to not use tap water as it contains chlorine and possible chloramine so those people say you should only rinse out filter material in cycled tank water. For my own practice I use tap water and I'm never concerned with the tap water chlorine or chloramine.TIP ► In doing filter maintenance only do ONE SIDE at a time. Since the beneficial nitrifying bacteria is held in the filter material if someone were to 'clean' the entire filter - all filter material, the tank can be put into a mini-cycle. Not really a good thing. Only clean 50% of the filter per time, doing this will give a more chemically stable aquarium.TIP ► A dirty filter is a wonderful filter. While you don't need to live with 50% water flow rate from the original brand new condition, people hurt their tanks by cleaning filters too frequently. The nitrifying bacteria is held in the filter material so cleaning the filter too often will easily cause a mini-cycle which will always put stress on livestock. Crystal clear water = dirty filter. Clean filter = zero cycle. Might sound strange but it's the truth.TIP ► If you hear the word ' cycle ' with this hobby that is in reference to a naturally and beneficial occurring chemical process where ammonia is converted to nitrite and then over to nitrate. A brand new tank will take aprox 30 days naturally for this to happen. At that rough 30 day mark PPM readings will be 0 ammonia, 0 nitrite and a reading of nitrate. In terms of fish you need really nothing for nitrate so your reading can be low however if you have live aquarium plants a reading of nitrate is mandatory.TIP ► In all my impeller filters, right out of the box I use a small dab of 100% pure petroleum jelly and rub it all around the magnetic part of the impeller. This will help with lubrication and a small tweak we can do to even further make the tank more quiet. Not gobs are used just a thin coat. I've done this for a very long time and there have been ZERO negative effects in any of my tanks. If this is not done, that beautiful slime coating found in mature aquariums will form within a couple weeks and naturally coat the impeller. I still just use the petroleum jelly anyways.TIP ► Please be very careful about filter placement especially if someone has fine substrate material especially such as sand. This can easily get sucked into the filter and once it hits the impeller it could easily give a louder grinding sound. When people come to me about grinding filter noise this is the first thing I ask them to check. Make sure the impeller cage is 100% clean of any debris. I typically say no closer than 4" so the substrate bottom when people have those fine grain substrates. Standard type gravel size which I only use, I can let the filter stand right on the substrate itself.TIP ► If by chance you have any sort of filter that the impeller appears to be caked with material and cannot be washed off just use a fine piece of sandpaper. Something like a 200 grit is what I have used in the past to make sure there is nothing 'stuck' on the magnet that can cause unwanted noise. This goes to any brand of magnetic impeller filter. You don't need to grind the magnet away just make the surface clean once again.TIP ► My first tip above talked about a dirty filter being wonderful and people clean it too frequently. This is 100% the case...however if your filter requires cleaning more than every 2-3 weeks then it is not the filter but the tank itself has a maintenance issue. If could very well be a buildup of mulm/detritus from lack of regular tank maintenance. Your filter will collect floating debris however if there is too much floating debris then any filter no matter brand or size will clog. That is our issue not a filters issue of not functioning properly. An aquarium filter's purpose is to COLLECT floating material not to magically make floating material 100% disappear. It is OUR regular maintenance job to remove that collected material.TIP ► A simple way to see if a filter is working properly, HOB, underwater or whatever is if water is being moved by the output. If water is being moved, the filter itself works. If the water is only moving 50% from original flow rates that means it is a very dirty filter that needs our cleaning maintenance...the filter did it's job just fine as it collected the floating material....the 50% flow rate is our issue with tank maintenance.There is much more I can write but I'll cut it off there. Good luck with the hobby, keeping aquariums is a wonderful thing.This brand is legend...please don't let someone else tell you otherwise.=====================Overall: 10/5 Yes a 10 out of 5. Fluval filters are amazing.Suction power: 5/5Easy to clean: 5/5Noise level: 5/5=====================Helpful, is how I hope you find my review

21.8.2010

Good points:~ Very easy to assemble.~ Very quiet operational noise when not using the 'airflow control venturi device' because there are no bubbles.~ Easy to clean and maintain.~ My goldfish are very happy!~ Not as unsightly as other filters on the market.~ easy to follow concise instructions with pictures and in many languages.Bad points:~ Regular (weekly) rinsing of the sponge is required, otherwise the product does not work eficiently.~ A little noisy when making use of the 'airflow control venturi device'.~ No carbon filter.Review:I bought this product through amazon about a month ago, and have so far found it to be a very effective water filter for my three goldfish. My fish are quite large,

10.11.2016

I purchased this filter for an tropical aquarium with a 14/15 gallon capacity.The dimensions of the aquarium is (h)30cm x (d)30cm x (w)60cm. I find that this filter is the perfect size for the aquarium with a strong flow that can be slowed down and enough filtering gallon per hour to deal with the waste in the aquarium.In this tank I have:- x1 platy (male)- x1 sword tail (male)- x1 betta (female)- x2 albino corydora- x5 neon tetra- 6 Assassin snails- Plants- A few Amazon sword- Floating Water wisteria- Quite a lot of Java fern on bog wood- About 1/6th of the aquarium has guppy grass covering the area- 3 Marimo moss ballsI find that with this set up I only need to do a 25% water change every 1

23.9.2012

I have a 120L tank which was served by Fluval U2 originally. It was a good filter but of course not having the the capacity to cope with the size of the tank, hence I upgraded to Fluval U4. I have always been a fan of the Fluval product though pricey at times. However, I need a reliable filter which not only does the job well but last longer than the ones I had.Build:As one would expect from Fluval, the design of their product has always been at the forefront of water filtration system. U4 is no exception. The layout is well thought through with large grilled surface on both sides drawing large area of water into the filter.

13.3.2015

The Fluval U3 Underwater Filter 800LPH the 3rd one I've had. The first was a U2 and it lasted for years, ran really well and was very quiet. The second was a U3 like this one, but I brought it from Ebay second hand and well, I won't be doing that again. After 2 months it just stopped working, even with a change of fuse. My fault entirely!So, I bought this one as it was a decent price for filters suitable for aquariums 90 - 150 litres in size. At the time of writing it's on offer, so a big saving.This filter has a system where you can fix it into the tank and when the carbon cartridges, sponge filters and granules need changing you just tilt, open the lid and remove the cases they are in,

6.2.2021

I brought a 60x30x30cm tank kit with a basic pump for tropical fish and was always struggling to keep up with the cleaning. My tank has a few tetras and guppies and takes about 50 litres, it also has some live plants and some snails which invited themselves in. The old pump just couldn’t keep up and after 6 months it had reduced to a trickle despite cleaning it regularly. This pump is very big in the tank but within minutes I could see a difference and the water stays cleaner for much longer now.The pump has three removable sections from the top with two filled with coarse, medium foam and a charcoal filter. The center section has the bacteria medium to allow good bacteria to help filter the water.

30.5.2015

Excellent filter, NOT so excellent Carbon / Filter Pads.This filter becomes 200x better if you don't use the Fluval Carbon / Filter Pads;- Instead purchase a huge roll of Filter wool & a bag of Carbon (much cheaper than the fluval stuff).- Then cut the Filter Wool down to the size of the cages that slide in and out and push it firmly into place.- Then the blue cage that holds the Ceramics place some carbon inside of it too (DO NOT over fill it)I used this Filter for around 8 months with Fluval made filter media etc and it was only "ok" decided to purchase the above items and design my own way of filtering my water by modifying this filter and it works extremely well,

20.11.2011

I've been fish keeping for almost 4-years and this by far and away the best filter I've owned. In the space of time, I find it amazing just how much filter technology has come along, and the U-Series of Fluval products demonstrate head-slappingly logical design with quality components. The fact that the actual filter housing (that being its outer shell) can be allowed to remain is a god send, for it allows the user to open the hatch and just remove the filter media vertically. No mess, no fuss, and all in a fraction of the time it would take with the previous generation of Fluval filters.The filter media included are encased in their own specific shells, meaning that you not only keep your hands cleaner when doing work,

1.4.2013

I have a 95l aquarium and I was recommended to get this filter as it is suitable up to 110l tanks. You need to attached the suction cups on the back of the bracket, you then need to attached 2 outlets to the front of the filter. Once done this position it in your aquarium. In my 95l tank it does look big, but we were wanting to buy loads of plants anyway, this will hide the filter. There is 2 great functions about this product.1. It has 3 desperate filter chambers inside. These contain 2 chambers with foam and carbon pads and the other is like small pasta shapes which cleans your water.2. It has a dial on top to adjust the flow of water.

19.9.2013

had one of these for a few years and now about to replace my old one with the same model..cause i love it :)a few of the reviews are stating that the power drops off or the U2 needs a bang or thump to get it going, what i think might be happening is its not being taken fully apart to clean, the bottom of the casing can be released by pinching both ribbed areas on the bottom and pulling downwards, seperating the two parts revealing the impeller, remove this and give it a good clean (and the hole it comes out of)ensuring that the magnetic forces can work to spin the thing (impeller) also mentioned was the mess and poop that is released into the tank whilst cleaning... not when i do it (smugness suits me)get a bucket,

3.6.2012

brought this as a friend had one and had nothing bad to say about it, previously had a aqua one 103f which kept getting tetras stuck behind it and killing them as it has a small inlet behind it which was strong enough to cause problems.this filter is hans down better- its quiet except for the usual gurgling from the Venturi tube which i have turned off, filters are huge in comparison to its predecessor and cover both sides, i cant speak for myself on this but my friends is 4 months old and hasn't needed cleaning once.its also nice that the bio media is separate so it doesn't have to have a mini cycle when you clean sponge however the cartridge this biomax media fits into is large enough to

23.10.2010

This filter, suitable for aquariums 90 - 150 litres in size, is relatively quiet and easy-to-use. There are three types of filtration provided - granules in a central compartment give biological filtering, mechanical filtering is carried out by the sponge filters, and carbon cartridges will clarify the water and remove harmful chemicals. Note that the carbon will also remove some medications from the water, so be careful with a sick fish.The price seems fair, although the recommended replacement rate for parts means buying new carbon cartridges every few weeks, foam pads every few months, and replacing a few of the granules every 6 months. Aquarists may argue over the necessity of such frequent changes,

3.11.2016

I have a 90 litre tank and it came with a Fuval U2 filter, but it just was not right. This U3 filter is so much better for my tank. My plants and fish are doing so much better now than with the U2, which was working at the uppermost limits of its capacity. I swapped the carbon filter inserts for the new Fluval Poly Clearmax, which do not remove plant food etc, as the carbon filter inserts will, and my plants are really doing well.If I had to add any negative points it would be in the printed instructions. They do not explain where the Fluval clear and clean cartridge should go. I had to Google what it was, as it fell out of the box in white packaging and almost went in the bin with the empty box and bags.

27.4.2012

I had a Interpet PF1 filter in my 65 liter fish tank but found the water was turning brown after water changes (filter is rated for this tank). The main issue I had with this filter was the fitting of the top of the filter with the bottom body did not have a tight seal, which mean water was being sucked through the hole where the power adjust is. As a result of this 3 small fish were sucked into the filter and died, and a snail was also sucked into the filter.The U2 filter had good reviews so I went for that. The filtration is much better than the old filter, with the water flowing through the whole pad, as opposed to just the bottom of the filter pad.

3.6.2020

I have two fluval U2 filters running in my two tanks.The filter is very very quiet. Two sponge pads each with two different sponge system in the pad (your choice what you going to put in the pads) plus middle pad for filter media. 3 different mods to choose (first-top strong water flow with bubbles if the filter is sticking a bit out of the water level but then the bubbles can make a bit of noise. Second-light water flow with three different directions to choose. Third-down strong water flow with no bubbles even if the filter is sticking out of the water level). For sponge pads I am using white sponge for big debris with addition of carbon and fine cotton foam pad and for filter media I am using biomax from fluval.

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