# Sump vs Canister Filter.



## jonathantc08

I currently have a 90gal with 2 Eheim 2075's.It's freshwater and I have African Cichlids. When I bought my aquarium it came with a 30 gallon sump. I have been thinking about it and the extra 30 gallons of water could really do some good because I am heavily stocked. I also like the fact that I can hard plumb everything. The Eheim filters use alot of proprietary pieces that are not as easy to fit. I would need to use an external overflow because I tested the glass and it's tempered so I will not be cutting it.

main reason I want to use a sump is to move my equipment out of the tank and add water volume.Also I like how the overflow skims the water surface.

I don't really want to hear all you salt water folks about how it's a waste for freshwater, because the sump serves the same purpose for freshwater as saltwater even if the equipment you intend to put in it is different.


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## metricliman

So what's your question? 
Go for the sump + 1 canister. Keep the other canister around for another tank.
Is the whole tank tempered or is it just the bottom?


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## ShortBus

jonathantc08 said:


> main reason I want to use a sump is to move my equipment out of the tank and add water volume.Also I like how the overflow skims the water surface.


Having a sump opens up your options with adding extra filtration for your setup, usually the bottom is the only part that is tempered, you could still drill the back of the tank.

+1 :thumb:


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## nodima

A sump and canister is a great solution. I've used HOB overflows for years (10) and only had an issue once, and upon review that issue turned out to be directly user caused!


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## Randy_G

I used an HOB and canister for a few years with my previous tank. With my new tank I am going with a sump. It's a 72x18x15 (inches), and I want the flexibility of the sump. I also wanting the extra water volume, and like the idea that the heater is out of sight and not in the main tank. Canisters are nice and quiet, and for their volume do a lot of work.


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## jonathantc08

yeah I appreciate all your comments... I think i'm going to stick with my eheim's because I cannot drill the back of the the glass is tempered all around. I had a glazier come and look at it and he recommended not drilling it. So I would have to use an external overflow box and I don't know how to make them fail-safe to prevent flooding.

If I ever setup another tank I'm definitely using the sump over canister.


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## ShortBus

Here is a quick tip on how to tell if the glass is tempered
http://tinyurl.com/7kv3dll


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## nodima

jonathantc08 said:


> yeah I appreciate all your comments... I think i'm going to stick with my eheim's because I cannot drill the back of the the glass is tempered all around. I had a glazier come and look at it and he recommended not drilling it. So I would have to use an external overflow box and I don't know how to make them fail-safe to prevent flooding.
> 
> If I ever setup another tank I'm definitely using the sump over canister.


There are far worse tihngs than to be "stuck" with a pair of eheims! 

As for making an overflow box failsafe - I'm not sure anything (even eheims) are fail-safe. In 10 years of running with an overflow box, the only issue I ever encountered was it running dry and losing prime once, and that was completely my fault. FWIW I used the marineland SOS overflow. Assuming your sump's pump chamber is reasonably sized relative to the tank, you should not have an issue with over filling your tank. By reasonably sized, I mean will not pump the entire sump back into the tank due to the pump chamber having a baffle between it and the rest of the sump.


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## b3w4r3

An overflow box is basically fail safe. The box hanging inside the tank will only allow the water in the tank to drop to the level of the U shaped holes. The siphon between the inside tank box and outside tank box would have to lost its siphon to have a problem there, and I have never had anything like that happen.

The box inside the tank is usually adjustable up and down which lets you set the level of the tank water. If this box came lose and dropped lower than where you set it, or fell into the tank completely, you would also have a problem, but again it's not likely to happen if you check the tightness of the fasteners regularly.

The last thing to consider is the return line. When the pump is shut off, or the power goes out, water will siphon from the return line until the water level drops lower than it and allows air to break the siphon. You deal with this by making sure that the return nozzle is not far enough under the water surface that it would flood the sump when the pump is shut off. It can also be dealt with by drilling a small hole close the the water level in the tank. That way when the water begins to siphon back through the return line is will suck air and stop the flow.

It's just a balance thing you have to work out. I think a proper sump with a wet dry section is probably one of the best systems for biological filtration used on aquariums. Plus they are a lot easier to maintain than other types of filters.


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## jonathantc08

Thanks for the reply b3w4r3

The return pump losing power is definitely a problem because the sun room my aquarium is in has a faulty breaker.. I guess I could always replace the breaker but not only that living on california's power grid we usually have 1 or 2 power failures a year.

as far as being stuck with eheim. they are the best filters I've ever used and if I ever used a canister I wouldn't choose any other but eheim. I do admit the eheims don't have a good gph flow rate but that's why I have two 

now if i could just get those particulates out of the water 0_o


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## Randy_G

To prevent water backing up from the tank in case of a return pump failure, or power failure, just get a 1 way valve. Water is allowed to pass in 1 direction only.


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## ShortBus

I would stay away from the one way valve
With a siphon break you should be ok


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## kmuda

There are some very basic preventative measures that can be taken to eliminate the power outage/back drain/flood isssues.

1. Do not have the outflow (in the main tank) from the return pump submerged. Have it above the water line. If the power fails, no water will siphon back into the sump.

2. Do not have your return pump located in the bottom of the sump. I use simple trays I bought at Wal-Mart. The return *pumps* (notice I said pumps... get to that in a minute) are lifted (sit on these trays) so that if the overflow looses siphon the return pumps will only return enough water to fill the main tank to the top without overflowing. The pumps may run partially dry and may become damaged, but you will not have a flood.

3. Do not fill the sump completely. In the event of a power outage, the main tank will only drain until the water level falls below the level of the overflow, at which point the overflow will stop siphoning (but the siphon should re-establish itself when the water rises back to normal levels). With a little experimentation, you can figure out how much empty space you need to leave in the sump to allow the tank to drain below the level of the water flow without overfilling the sump. In my 20 gallon sump on a 100 gallon tank, I only need to leave about 3" of empty space in the sump to account for this.

4. Purchase an overflow box with a Tom Aquatics Doser Pump connection on the siphon. This doser pump connects via airline tubing to the overflow tube, preventing the overflow from ever loosing siphon. If something like a power outage does occur that could cause a siphon break the doser pump sucks water back into the overflow, recreating the siphon. During normal usage, the doser pump prevents air bubbles from accumulating in the overflow tube, eliminating another method of loosing siphon.

5. I use two lower gph pumps as return pumps instead of one large one. Water is only going to drain into the overflow at the GPH of the return pump. I use two 300GPH pumps so during normal use, water drains into the sump at 600gph. If one pump fails, nothing goes wrong, the flow rate through the overflow just drops to 300gph. Heck, even if you had a small secondary pump running at 30gph this would prevent problems in the event the primary pump fails for any reason.

It all sounds a lot more complicated that it really is. Nor do I really use my sump for filtration. It's there to extend my water capacity by almost 20 gallons. The number one solution to pollution is dilution. That extra 20 gallons can be the difference in 5ppm of nitrate creep per week. That and I offload some equipment to the sump (heaters, an HOB filter). Recently, I've used my sump to add a Dr. Tim's NP-Active Pearls Reactor (for further nitrate reduction) and associated necessary mechanical filter. Below is a pic. One return pump runs through a 100 Micron Whole House filter (bought at Wal-Mart for $25) for enhanced water polishing, the other runs through a UV sterilizer. The flowerbox is a DIY Mechanical filter which supports the return pump from the NP Pearls reactor.










Also in the sump are two large air-drive sponge filters rated at 75 gallons each. These are my emergency filters. In the event of an extended power outage they get moved from the sump to the main tank and connected to battery powered air pumps. In day to day use, they have excellent gunk removing capabilities you will not find in other type of filters.

All mentioned to express that sumps can serve more of a purpose than to replace canister filters. This same tank runs 3 separate canister filters. The purpose for the sump is to extend water volume and to house beneficial equipment that would be too ugly to keep in the main tank.


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## metricliman

I applaud you, kmuda. Excellent research and writing. =D>


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## kmuda

Thanks. Many years of flooding the floor before I figured out how to do it right. I'd have a flood, figure out what went wrong, fix it, and go onto the next one. I think I got it all covered now. A flood at this point would be at the "act of god" level. :lol:

I misspoke on one point. The mini pump I referenced as the Tom Aquatics Doser Pump is actually called the Tom Aquatics Aqua Lifter pump. It's basically an air pump in reverse. Eliminates many concerns. Even if your overflow box does not have the airline connector for this pump, work a section of airline tubing up into the U or J tube of your overflow, until it reaches the top, connect up the Aqua Lifter pump, and you've accomplished the same thing.


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## ShortBus

Personally I wouldn't use a wier type overflow they fail way to often and need a pump to make them work. The standered utube have a much better track record. They have only ever failed on me becouse I let algea build up and block the flow. Drill or use the utube types


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