# Sump vs. Wet/Dry vs. Canister



## fishscale (May 29, 2007)

What defines these different methods of filtration? Could it be argued that a very large sump that is completely sealed is basically a canister? This might be a stupid question, but what's the big difference between a wet/dry and a sump? Some posts just got me thinking, and this is probably a stupid thread, but what exactly makes a wet/dry a wet/dry? My understand is that you have the "dry" portion to increase aeration. Could you not have a wet/dry in a sump? If you sealed the sump, would this be considered some form of giant canister? Could you inject CO2 using a sealed sump, and reach a point where the air inside the sump was saturated enough with CO2 that you wouldn't lose any from the wet/dry action? Of course, this would kind of defeat one of it's purposes, and this is a thread created very late in the night/early in the morning, so I'm not thinking too clearly, but I'd just like to hear some people's thoughts on it.


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## Sympley (Apr 18, 2006)

The way I see it(of course this might be wrong):

Sump: Pretty much an extra volume of water, and a place where you can hide your equipment like heater, CO2 ractor etc. Does nothing for filtration purposes, unless you have a marine tank with protein skimmer in there. Or a sponge that might take out some detirus (mechaincal filtration). You can also dump in some carbon, or phosphate removers (Chemical filtration). For the purpose of this tread I will asume we are discussing jsut a basic sump.

Wet/Dry (What I have): Very similar to sump except you have an area with bio-balls where the bacteria can colonize. Usually there is some room as well for equipment.

So for a sump to be a big canister, I don't think so, for a wet/dry to be a big canister kind of. Canister has some mechanical and biological filtration, I put filter floss in my wet/dry and it is does a nice job as mechanical, and the bio-balls to the biological part.
I think if you would seal a sump and inject CO2 it would be like a big CO2 reactor, not sure how efficient though. If you would seal a wet/dry and inject CO2 it would also be like a big CO2 ractor, I just wonder if it would kill the bacterial that is colonized and needs air.

Just my 2 cents.


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## stev0205 (Nov 5, 2007)

canister = no overflow
sump/wet dry = overflow
as far as i'm concerned sumps and wet/drys are essentially the same. i believe sumps can filter if you design them to


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## Ransom (Mar 3, 2006)

A sump is just an additional body of water shared with your main tank. There is no filtration implied in the word sump. However, most sumps include some form of filtration, but you could have one just to expand the water volume if you wanted to - it would still be a sump.

A canister is a basically a one-piece sump and includes a built-in pump. If you add filtration stages to it, it has filtration in it, but if you left them out, it would still be a canister.

Wet/dry is a particular form biological filtration where the water trickles past some bacterial medium that is also exposed to air. You can have a wet/dry stage in any filter system. In a sump, in a canister (ehiem makes one), in a HOB (biowheel), or even in an internal filter (Hagen makes one but they don't sell it in the US anymore).


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## Divine Winds (Feb 16, 2008)

Foster and Smith had an article on their page. They categorized the different setups as In-line pressure and in-line free-flow. Perhaps they might have more info.


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## stev0205 (Nov 5, 2007)

Another difference to remember is that a canister works off of positive and negative pressures created by siphoning. Since the canister is a completely sealed off system, the motor has a lot less work to do when it comes to how much head it has to overcome, etc...


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## intermediate_noob (Jan 23, 2007)

As Stev0205 says, the cannister works off a siphon whereas a sump/wet-dry setup just uses an overflow. Another way of looking at it is that a cannister is a closed loop system. When the power goes out, the cannister does not continue to take in water because it is sealed. This is why people like Tom Barr use inlets and outlets that go through the bottom of the tank and stick up only a few inches from the substrate.

With a sump or wet/dry there is nothing to stop the water. So if the return or overflow continue to siphon water, it will continue until the siphon stops. check valves can stop this and so can a siphon break ( a hole drilled in the return line to take in air when the power goes out or pump is shut off).

I have a wet/dry on two of my tanks and they work fine. I thought they would be cheaper than a cannister but really this is not the case when you add everything up (pump, media, etc.). The other thing is space, a sump and wet/dry normally take up a lot of real estate under your tank. Sumps are also good for dosing ferts as you do not have open the hood and normally allow for a wider range of different filter media (in some cases).


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## stagius (Nov 26, 2007)

Why people use the sump anyway? Would the wet/dry be always better version of sump?

Is is true that a sump or wet/dry can main water level in the main tank by a floating sensor ?


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## stev0205 (Nov 5, 2007)

the sumps keep the water level in the display tank constant is by using an overflow... you don't need a floating sensor to keep it constant


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## stagius (Nov 26, 2007)

will the wet/dry do the same thing ? 
Is it efficient to setup a sump in small tank like 20-30G ?


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## indyglyder (Jul 14, 2006)

If you have a drilled bottom tank the height of the pipe plus the surrounding plastic box determines how much water will still flow out in a power loss. I have a oceanic 90 with mega flow and it only allows a few more gallons out after the pump is turned of. its a good design. wet/dry will off gas your co2 if you don't use co2 go ahead. I'm working on a sump with filtration that hopefully will not lose to much of my co2. 
benifits of sump. 1. hides unwanted stuff 2. more water 3.easy to add auto top off 4.can be under tank in cabinet. 4. if drilled bottom no hoses outside tank. 5.can be faster to clean than canister if designed properly. 
6. keeps water level the same. disadvantages. 1. co2 offgassing 2.need a drilled tank or overflowbox. 3.?


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## Craigthor (Sep 9, 2007)

I use a DIY sump that keeps all of my bio fitration submersed and has a DIY 100 Micron filter sock for filtration. Also allows me to keep my heater and stuff hidden and gives me about 20 extra gallons of water in my 75.

A Wet/Dry has water flowing over the biofilration that allows for oxygenation as some of the media is wet and some dry similar to water from a waterfall that some raock are wet and some are dry as the water rolls off of the cliff.

Here is a couple of pics of my home built sump.










Craig

Edit: I also have my auto top off setup water comes in te tank and leaves the sump to a drain in my basement via a DIY overflow in my sump. It keeps my levels even all the time. Also water coming in to the sump comes in under the water line so very little off gassing happens.


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## intermediate_noob (Jan 23, 2007)

Here is a good forum post about off gassing with CO2

I do not know if you could really quantify how much more is lost by using a sump, but the overflow is where the bigger issues occur. 

http://www.barrreport.com/co2-aquatic-plant-fertilization/3432-c02-large-tanks-trickle-filters.html?highlight=c02+large+trickle+filters


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## Aqua Dave (Feb 23, 2004)

A sump is essientially a wet/dry, without the dry portion. The part where the water trickles down over bio-balls in a wet/dry is the part missing from a sump. You can still have bio-balls in a sump, but they are submerged in the water. The trickle part of a wet/dry is what outgasses CO2 at a high rate. A sump can be anything from an aquarium with nothing in it to something with several dividers for funneling the water over bio-balls, chemical filtration, and mechanical filtration. Just depends on how elaborate you want to get.

The difference between a sump and a canister filter is how the system operates. A canister sucks water out of the tank into the filter and pushes the water into the tank. In a sump system the pump in the sump just pumps water from the sump into the tank. Gravity is responsible for the water in the tank flowing through the overflow and down into the sump. Water level in the tank will remain the same for a sump system, but will lower for a canister system. Evaporation shows up in the sump for a sump system.

David


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## Craigthor (Sep 9, 2007)

Aqua Dave said:


> A sump is essientially a wet/dry, without the dry portion. The part where the water trickles down over bio-balls in a wet/dry is the part missing from a sump. You can still have bio-balls in a sump, but they are submerged in the water. The trickle part of a wet/dry is what outgasses CO2 at a high rate. A sump can be anything from an aquarium with nothing in it to something with several dividers for funneling the water over bio-balls, chemical filtration, and mechanical filtration. Just depends on how elaborate you want to get.
> 
> The difference between a sump and a canister filter is how the system operates. A canister sucks water out of the tank into the filter and pushes the water into the tank. In a sump system the pump in the sump just pumps water from the sump into the tank. Gravity is responsible for the water in the tank flowing through the overflow and down into the sump. Water level in the tank will remain the same for a sump system, but will lower for a canister system. Evaporation shows up in the sump for a sump system.
> 
> David


good explination! :icon_smil


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