# Can you use a canister filter on a tank with a built in overflow?



## Nice Dreams (Oct 24, 2005)

This is my first post so be gentle. I am planning on putting together a 65g planted tank that has a built in overflow - I like the cleanest look possible. I want to use an eheim 2028 under the tank, but my lfs told me it's better to use a canister filter with the supplied intake, spraybar, etc. on an un-drilled tank because using it on an overflow would cause air pockets/bubbles in the canister filter and adversely affect the filtering process. Is this true?


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## harsaphes (Oct 10, 2005)

my tank has an overflow and im going to use a canister on it. Just put your intake away from your overflow.....i cant imagine it would be a problem.


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## edschmidt (Oct 4, 2005)

Were you referring to attaching the intake of the canister filter to the overflow drain? If so, this will not work well for the canister filter. It would be noisy and would not live very long with that amount of air being chopped up by the impeller. Regardless of whether or not you use the overflow for some type of a sump filtration or not, the canister filter can be used in conjunction with the other filter. The only stipulation about a canister filter is the intake and output should both be directly in the tank. Most canister filters do not have enough of a pump to drive any significant amount of head pressure...this means they shouldn't be plumbed out of a sump going back up to a tank either. Hope this helps.


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## Nice Dreams (Oct 24, 2005)

*No sump or other filter, I just wanted to use the Eheim*

I've never had a tank with an overflow, but I like the cleaner look of them. I wouldn't be using any other form of filter other than the Eheim 2028. I assumed it would a clean setup with the canister intake connecting to the drain in the overflow and the canister return connected to the return in the overflow. 
So, can I assume that most people that only use a canister on their tanks are not using a drilled tank and are using the supplied intake, spray bar, etc. that come with the filter and hang/suction to the back of the tank?
Is there any way to connect just the canister filter to the overflow without harming the canister filter?


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## unirdna (Jan 22, 2004)

This can not work using an overflow box, or any overflow system.

It has the potential to work with a drilled tank if the water level of the tank is high enough to completely cover the dril holes.

This seems like more trouble than it's worth (unless your drill holes are very low in the tank). You'll have to stay diligent with the water level.

Important point: When you use an overflow properly (with a sump), evaporation is reflected in the sump levels. Tank levels stay the same. So, if you try to use a canister, evaporation levels will show in the canister. It would only be a matter of time before you airlock your filter.

I would not try this. Even if you get it running, this is not a reliable system.

Scolley's tank is the exception. His drill holes are on the bottom of his tank, and he does not use an overflow system.


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## Nice Dreams (Oct 24, 2005)

*Thanks for the info.....of course I have one more question*

I appreciate the information, it will definitely save me some aggravation. Do many planted tank enthusiasts use a sump setup? Doesn't this form of filtration reduce the co2 levels in the tank and make more noise than it's worth. Why would anyone want to use a sump setup when they could use the included plumbing that comes with a canister filter? It sounds like sumps are better left to the saltwater tanks. When I mentioned using an overflow I was wrongly assuming that I could plug the canister into the overflow, I had no intention of using a sump. What are the benefits, if any of using a sump in a planted tank setup (outside of the minimal clutter in the tank)?


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## unirdna (Jan 22, 2004)

Not many planted guys use sumps. In almost all scenarios, a canister filter is the better choice.

That said, yep, I use a sump on one of my tanks :hihi:. I do this because it's part of my fish nursery. You can read more here http://www.plantedtank.net/forums/showthread.php?t=11069&page=7&pp=15. Over 6 months or so, I've tweaked it so it loses very little CO2 (I run 60 bpm), and is dead silent. Slow flowrate is the key.


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## Wasserpest (Jun 12, 2003)

Nice Dreams said:


> What are the benefits, if any of using a sump in a planted tank setup (outside of the minimal clutter in the tank)?


I think sumps can be cheaper than canister filters. They can be easier to clean than canister filters. They can be dimensioned the way you want it. They keep the water level in the tank the same. 

You decide if these are advantages big enough... or just use a canister filter the way it is supposed to. Most planted tankers are rich and use canister filters. :wink:


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## DiabloCanine (Aug 26, 2005)

Is your tank drilled? If not, IMO you would be way ahead to drill it. Using a sump over a cannister is a matter of preference. I have both, am looking at drilling the rest of my tanks to install overflows/sumps. There are several advantages to using a sump over a cannister:

1. All hardware is hidden including CO2 reactor, heaters, uv sterilizer, plumbing, etc.

2. More water in the system, i.e., I have a 110 gallon tank with a 30 gallon sump, gives me 110 gallons of water, can be significant if you have a deep substrate taking up water space. More water is better.

3. Rarely needs cleaned, I've never had to clean mine but my fluvals require monthly cleaning, messy and time consuming especially if you have 5 cannister filters to clean.

4. CO2 loss is minimal is setup properly, need to tweak oxygenation in the sump which can be effected by overflow rate, i.e., more flow = more oxygenation and out gassing of CO2. Low flow is not a problem with a heavily planted tank, plants are excellent filters.

5. Easier to control additives/supplements i.e., if using peat to lower PH you can use a media bag and just pull it out when you want to. If you put peat in a cannister filter, and want to stop, you will need to pull the filter apart to remove it. Same holds true for phosphate sponges, once you get phosphates where you want them, you just pull the media bag. Much easier to charge/control media with a sump.

Keep in mind water flow will depend on the size/number of openings in the overflow. A cannister will work but you will need to ensure the intake does not drain the overflow, i.e., gph rating of cannister filter vs water movement of overflow. If you decide to drill the tank and use a cannister, here is a bulkhead fitting for the intake:

http://www.jehmco.com/PRODUCTS_/HARDWARE_/Bulkhead_Fittings/bulkhead_fittings.html

If you decide to drill and use a sump, make a sump that is covered and has minimal turbulence. I would recommend this standpipe which eliminates the dreaded toilet flush sound:

http://www.dursostandpipes.com/

BTW, reefers do inject CO2 into their calcium reactors and most have a good setup for eliminating sump noise. Here is a good place to find info:

http://www.reefcentral.com/


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