Best Hang On Back Overflow Box: Reviews | Aquascape Addiction

Best Hang On Back Overflow Box: Reviews

As an Amazon Associate I earn from qualifying purchases.

Our 5 picks and reviews make finding the best hang on back overflow box a simple task, we have researched and put together very detailed reviews of the top contenders to help you.

Best Hang On Back Overflow Box: Reviews

Overflow boxes are some pretty convenient aquarium accessories no doubt. Their biggest benefit is of course that you can use them to house more and bigger equipment, items that you want hidden form your display. Pumps, sumps, and filters of all kinds just don’t look too nice, which is where the overflow box comes in.

Today we went to take a look at some of the best hang on back overflow boxes out there (this is our top pick), with the purpose of helping you find the one that works best for you.

Our 5 Picks

If you are in a rush then here is a list of the 5 products covered.

  1. Eshopps AEO11005
  2. Aqueon Hang-On Overflow Box
  3. CPR CS90 Overflow Box
  4. OF 600 Overflow Box
  5. Tunze Hang on Back Overflow Box

What We Think Is The Best Hang On Back Overflow Box

Let us start off by taking a look at our pick that we personally feel is the top contender. It’s got quite a few nifty features that you might really appreciate.

Eshopps Pf-800 Overflow Box

This is honestly a very simple external hang on back overflow box to go with. It is simple to use, it is durable, and it gets the job done. There is not too much to say about it, but then again, as long as it works, this really does not matter.


The Eshopps Pf-800 can be used for any aquarium up to 400 gallons in size. What is really neat about this thing is that you can use it for small aquariums such as 30 gallon tanks, or for anything up to 400 gallons as well.

Something that comes in quite handy here is that it has dual drains that lead down to the sump, or back into the aquarium if you so choose. In case one gets clogged, there is another one as a backup.

It helps to stop the Pf-800 Overflow Box itself from overflowing. It’s a very simple to install hang on back overflow box. More or less, just hang it over the back of your aquarium, put the syphon in the tank, and connect the drain tube to the sump.

Furthermore, the Pf-800 comes with cylinder foam pads over the drain pipe, which is pretty convenient as well. This more or less acts as a flow regulator, plus it helps filter solid debris out of the water as well. In other words, it cleans the water and makes sure that the drain pipe does not get clogged.

This thing is very durable and well-built. Only the highest quality materials were used here. At the same time, it is actually pretty lightweight, and not all that bulky either, which helps with setup and spatial requirements. One complaint is that it is a bit loud, very loud actually, but none the less, it does get the job done.


  • Durable.
  • Space friendly.
  • Does not clog easily.
  • Has a foam filtration pad.
  • Very easy to set up.
  • Works for small and large aquariums.


  • Very loud.
  • Fitting the hoses can be a little difficult.

Click here to check the price at Amazon

How To Choose The Right Overflow Box

Choosing the right overflow box for you and your aquarium is really not that hard at all. There are only a few considerations to keep in mind, so let’s talk about those right now.

Internal or External

We’re going to talk about the differences between internal and external overflows in more detail below. However, the main thing to keep in mind here is that external overflows don’t take up much space inside of the tank, plus they tend to be much easier to install than internal overflows.

With that being said, they are usually more expensive and a little less versatile than internal overflows.

The Size

The most important consideration to keep in mind when looking at an external overflow box is the size of it. Now, you do need to keep the spatial requirements in mind, especially in terms of the clearance behind the tank. However, this is not actually what we are talking about here.

You need to get the right size of external overflow box according to the return pump from your sump. For instance, if your return pump is rated at 250 gallons per hour, you will want the overflow box to be rated for at least 300 gallons per hour, if not about 350 gallons per hour.

The Drains & Filter

A convenient thing to have when it comes to overflow boxes is dual drainage pipes. Yes, single pipes work just fine in most cases, but if the single pipe gets clogged, the box will overflow, which is bad. Having an overflow box with dual drains means that if one gets clogged, the other can pick up the slack.

At the same time, having foam filters over the drain pipes is ideal, as they help to stop solid debris from flowing into the sump and they help prevent clogging too.

Types Of Overflow Boxes

In terms of overflow boxes, there are two main types that you can go with, those being the interior and exterior types, otherwise known as internal and external.


The first type of overflow box is the internal kind, the one which many people prefer. However, as you can see from our own reviews, this particular article is all about the external kind. Now, the reason why many people prefer the internal kind is because they tend to cost less, be quieter, more efficient, and have more capability in terms of room and accessories.

However, the problem with internal overflows is that they require holes in the aquarium. So, either you have to buy a tank with pre-drilled holes that are an exact match to a specific overflow, or you have to drill the holes yourself. This can be a bit tricky. Far too many people have completely destroyed tanks trying to drill holes.

It is by no means an easy feat to accomplish. At the same time, internal overflow boxes can be a little hard to install, as they also require special connections, gaskets, and other mounting accessories.


The other type of overflow box is the external overflow box. As we have mentioned, these are usually less desirable in terms of their efficiency, room, and accessory connectivity. However, the big benefit is that they are very easy to mount and install. You just have to hang them over the back of your aquarium, hence why they are sometimes referred to as hang on back overflow boxes.

Also, they do not require an aquarium to have holes in it. Not needing to purchase an aquarium with pre-drilled holes, or not having to drill them yourself, is a really big bonus. For this reason, we personally prefer the external overflow boxes as opposed to the internal variety.

You might also like our Protein Skimmer buying guide which you can find over here.

4 Other HOB Overflox Boxes We Like: Reviews

In case you are not a huge fan of our own number one choice, or if it is just not right for you, you can always check out these 4 other hang on back overflow boxes. They’re all top quality, really with only minor differences. Let’s take a look.

1. Aqueon Hang-On Overflow Box

This is another really simple and effective hang on back overflow box to go with. For one, it is made to be quite durable. No, the materials used are not of the highest quality out there, but they should last for a good few while assuming it's properly looked after.

The fact that it is so easy to set up is definitely an advantage. All you have to do is connect the tubing or hoses to your sump, hang the Aqueon Hang-On Overflow Box on the aquarium, and you are good to go.

The Aqueon HOB Overflow Box features dual drains, which is always useful. You don’t want your overflow box overflowing, as this will cause problems. In case one drain clogs, the other one will pick up the slack. The foam pad included here is pretty useful as well, as it filters out solid debris, thus cleaning the water and helping to prevent clogging.

This thing can be used for any aquarium up to 125 gallons in size. However, there is an option of this model that can be used for aquariums up to 400 gallons.

One thing that needs to be said here is that this particular overflow box is definitely not very good looking. Yes, it is quite durable, effective, and it gets the job done, but it is not stylish, nor is it quiet.


  • Good for tanks up to 125 gallons.
  • Quite durable.
  • Dual drains to prevent clogging.
  • Foam pad for some debris filtration.
  • Very easy to set up.


  • Not good looking.
  • Loud.

Click here to check the price at Amazon

2. CPR CS90 Overflow Box

This is another nice overflow box to go with, one that is rated for aquariums up to 100 gallons. If you have a decent home aquarium, this should be more than ideal for you. What is pretty cool about the CPR CS90 Overflow Box is that it features an adjustable water level, so you can control how much water is being syphoned from the aquarium to the sump. It’s an easy way to adjust the water level in the tank as well.

The bulkhead included here is perhaps the best way to drain water from an aquarium to a sump or to a filtration unit. It is quite efficient and it works pretty well. The black top of the CPR CS90 is also designed to help reduce algae blooms and buildups, which is pretty neat as fat as we are concerned. The CPR CS90 Box does have a flow rate of about 600 gallons per hour, which is fairly impressive.

This thing is quite easy to install, as most hang on back overflow boxes tend to be. This particular HOB overflow box also comes with dual drains, which once again, is great in case one gets clogged.

The drains both come with foam filter pads equipped, which helps to clean the water of solid debris, and to prevent clogging as well. This is a fairly space efficient model to go with, yet another bonus.


  • Space friendly.
  • Adjustable water level.
  • Dual drains to prevent clogging.
  • Dual foam filters for debris removal.
  • High flow rate.
  • Rated for aquariums up to 125 gallons.


  • Not the most durable.
  • A bit loud.

Click here to check the price at Amazon

3. OF 600 Overflow Box

This is a nice continuous overflow box to consider, one that works without the U-tubes. Not needing the U-tubes is pretty cool as far as we are concerned. The OF 600 Overflow Box has a flow rate of 600 gallons per hour and is rated for aquariums up to 125 gallons in size.

It should be more than good enough for most home aquariums. One thing to note here, unlike with the other models we have looked at, the OF 600 does not come with foam filter pads.

The OF 600 is very easy to install, just like all the other models we looked at. Just hang it on the back of your aquarium, connect the hoses to the sump, and you are good to go. It really does not get any easier than that.

While it is not the most space friendly design out there, it does get the job done. We personally like the ID bulkhead that it is included here, as it is quite efficient and effective.

The OF 600 Overflow Box only features a single drain, which is not exactly ideal when it comes to preventing clogs. However, what is really cool here is that the OF 600 Overflow Box is made out of solid acrylic and other very rugged materials. A lack of durability is definitely not an issue when it comes to this particular hang on back overflow box.


  • Very durable.
  • Good for aquariums up to 125 gallons.
  • High flow rate.
  • Fairly quiet.
  • Very easy to set up.


  • No foam filtration pads.
  • May clog on occassion.

Click here to check the price at Amazon

4. Tunze Hang on Back Aquarium Overflow Box

The Tunze Hang on Back Aquarium Overflow Box comes with a flow rate of 320 gallons per hour. It is indeed a very efficient model of hang on back overflow box to go with. Now, while it is actually not all that small, the box itself is not designed for larger aquariums. It’s a good option for any aquarium up to 100 gallons.

On a side note, if you get an additional U-pipe, you can use this thing and produce over 400 gallons of flow per hour.

The Tunze Hang on Back Aquarium Overflow Box is easy to set up, as it can just be hung on the back of your aquarium and connected to your sump. It is a self-priming model, which is really neat, plus if it shuts off, it will automatically restart without any issue.

The Tunze Hang on Back Aquarium Overflow Box is built to be very quiet, which is of course beneficial. Also, this particular model is built to be extremely durable as well. It should last for quite a few years.


  • Durable.
  • Quiet.
  • Can be upgraded with extra parts.
  • Self-priming.
  • Restarts automatically after shutting off.
  • Good for aquariums up to 100 gallons.
  • efficient.


  • Cannot see the interior – black walls.
  • Not too space friendly.
  • Big and bulky.

Click here to check the price at Amazon


As you can see, hang on back overflow boxes are very convenient no doubt. Some people might prefer the interior overflow boxes, but having to drill holes in your aquarium is just not a good idea no matter how you put it. We would of course recommend our own number one pick, but at the end of the day, all of the models we have looked at here could very well take the spot for the best hang on back overflow box.