# Sump filtration vs canister filtration



## Daveslaney (19 Jun 2016)

Hi
As a house move could be on the cards.So a total tank strip down is enevitable by the look of things.
It has got me thinking about filtrationon my tank also, Tank size is 300ltr.I currently use a tetratec 1200 filled with bioholme media for bio filtration,a fuval 306 filled with flter wool,carbon and puragen for mecanical.I also have 2 circulation pumps for added flow.Work pretty well to be honest.
My lfs can drill the tank for the wier no prob.So what im asking is whats the advantages or disadvantages of switching to a sump?Whats peoples experinces of using both?
Regards Dave.


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## Easternlethal (19 Jun 2016)

sump filters are superior and easier to manage if you're the type of person who has or likes to experiment with different types of filtration techniques and media.


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## Chris Jackson (19 Jun 2016)

I like that I can see what is going on in my sump and can very easily check, clean or alter the media. I have heater, ph probe and a co2 reactor all doing their thing in the sump rather than the tank which keeps things tidy. However setting up the overflow to be quiet and generally getting things just right has been far more complex than with using cannister filters and I can't really say the tank runs noticeably any better than my cannister filtered ones have.

I do plan to upgrade my other tank to sump filtration as well at next major re-vamp so yes I'm a convert but I also happen to really enjoy the diy side of things and tweaking stuff.


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## Daveslaney (20 Jun 2016)

Yes i like the idea of having all the equiment outside the tank and being able to easily see whats happening in the filter. I have made a co2 reactor along the lines of the one in your video with the underwater spraybar but filled with bac balls i run the up diffuser before the reactor the increased water movement in the reactor dissolves the co2 mist before it hits the tank, The only drawback is it reduces the filter flow a fair amount.So being able to use a separate pump for this from the sump would be a advantage too.
When we move the tank will be going in the conservatory.So easy access to drainage pipes so was thinking to have tank drilled anyways to have a overflow in the tank to waste drain,Then for water change days trickle water into the tank with a imput water line let it overflow down the pipe to the drain.
If i raise the water level in the tank this way would the water in the sump raise the same amount too or would the tank overfow first?Just thinking of putting overflow pipe in sump instead of tank is all.


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## Chris Jackson (20 Jun 2016)

With a sump, the tank water level stays constant at the level of the overflow. Any evaporation or overfilling alters the level in the sump only which is another bonus. For the overflow I suggest you look at http://www.glassreef.com/basics_overflow.php for guidance. If I were you I'd have a Bean Animal type overflow from the tank to sump and then an emergency or water change overflow from the sump to waste.

Some will suggest that sumps are a problem with CO2 off gassing but I have not found that to be a big issue at all. For stable co2 levels you need good surface water movement anyway to stop CO2 levels getting too high.


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## Daveslaney (21 Jun 2016)

Great info chris thanks.
I to have found with more surface water movement on the currrent tank,higher o2 levels i can run higher co2 levels if required with no aparent distress to the fish.So i see this as a plus for the sump too.
Great tanks you have there.Is that a hang on the side style overflow you have for your sump?


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## Chris Jackson (21 Jun 2016)

Thanks, yes that's a diy hang on overflow on my small tank but I'm currently planning a more elegant drilled outlet solution to replace that as it's a bit too much of a faff to keep clean and not quite the rght size.


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## Daveslaney (23 Jun 2016)

Why does the tank seem to run so good when it will soon be time to tear it down? Hehe..


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## Chris Jackson (23 Jun 2016)

very nice! They always get more stable with age.... 

I moved a 48 x 12 x 18 between houses by draining it almost completely and taking the fish in a bucket it was only a move of a few miles though and there weren't any huge rocks in the tank. All went well!


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## Daveslaney (24 Jun 2016)

Thanks.
I will prob end up getting some mates round and doing the same.


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## zozo (25 Jun 2016)

Few other advantages from a sump is, the overflow skims the surface, so there is always a skimmer reducing surface film building up. There is much more room for biomedia in the sump and if constructed as a trickle system the biomedia is optimaly oxygenated which triggers aerobic filtration, the pump always runs freely and minimaly restricted in flow since it doesn't need to suck the water through the filter media.A smaller pump can be used to get simmular capacity as with a cannister..

One disadvantage from a sump is if you use a syphon overflow box or pipe and if the syfon ever brakes the pump will empty the sump. You always need to calculate the water level in the sump not exceding the free volume of the tank so the tank can never be flooded if the syphon brakes.
So the height of the pumps placement is crusial, if placed on the bottom of the sump it might be to much water volume pump out. Then you also need to use a floater switch in the sump  so that if the sump completely drains the pump will shut off and never runs dry. You need to maintain a floater switch like this never to clog or get dirty, if it fails for this reason it will keep the pump running dry and the pump will burn out. But if you use a drilled tank, this is not an issue, this only applies with the use of syphons.

Another thing which isn't realy a disadvantage compared with a cannister but just a thing to keep in mind.. Because it only takes water as a skimmer from the surfafe the heavier dirt particles floating around mid level in the tank which are to heavy to ever reach the surface finaly will end up as debris on the substrate. with a filter inlet from a cannister they would have been sucked in long time before that.. So with a sump you might need a little more intensive substrate cleaning compared with a cannister.

To get an overflow silent is to make it not suck in air, with a syphon this is very easy with the use of a valve to calibrate the drain speed with the capacity of the pump. That way the whole outflow is always completely filled with water, if air bubbles are sucket in it will always make slurping noises. Using a hollow pipe in a drilled tank which has overcapacity will always make a sound of running water the air in a pipe can ampllify this significantly. So trimming the outflow capacity and equalize it with the pump capacity is essential to reduce nois.. Here we have a small disadvantage, if you dont like noise you need to use a valve and check this valve regularly so it never gets clogged. Then a floater switch again will come in handy, if the sump drains due to a clogged overflow the pump stops running.


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## Daveslaney (25 Jun 2016)

Is this the reason some people use the dry mounted pumps on thier sumps?Less chance of the pump burning out than a submerged pump?
Or is it just a different design of pump?


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## zozo (25 Jun 2016)

Daveslaney said:


> Is this the reason some people use the dry mounted pumps on thier sumps?Less chance of the pump burning out than a submerged pump?
> Or is it just a different design of pump?



I have no idea, it depends o the pumps construction.. Any pump no matter what medium runs trough needs industrial bearings to be able to run dry.. These are rather very expensive self priming pumps, i can't imagine someone using these in an aquarium setup, even don't know if they exist in such small dimensions, maybe for very large tanks. I use the excact same pump on my cannister as i use in my sump, on the cannister it's mounted dry on the in the sump it's submersed. They need water flow mainly for cooling and lubrication purpose and need a counter pressure to ballance the impeller.


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## Chris Jackson (25 Jun 2016)

A lot of pumps can run dry or submersed. Running submersed makes for simpler plumbing, requires less cabinet space, and also makes better use of the the pumps heat to warm the aquarium (unless you happen live somewhere where this is a hindrance). Sumps can be set up in many, many ways and you don't even have to have a surface skimming weir. It's all these options and choices that make things complex compared to canisters but for sure sumps offer the optimum in filtration performance and flexibility.


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## zozo (25 Jun 2016)

Chris Jackson said:


> A lot of pumps can run dry or submersed.



You are mixing up something here Chris .. Running a pump outside a medium in our case water, what  you call dry,  doesn't mean the pump can run dry Internaly. It still needs a liquid medium inside around it's mechanical parts to run properly. All pumps consructed without industrial ball bearings and which are constructed with simple plain bearings. In our case usualy teflon and ceramics need the medium which it transports as lubrication and or cooling and stabilisation.

For example the pump of your heating installation in the house which looks like running dry, since the boiler aint particularly placed submersed in boiler room.. Drain the intsallation from water and make the pump run, 99% change the pump will make rather strange noises with in a few minutes and probably wont last an hour. Same goes for the cooling liquid pump of your car wont last running dry internaly. And these pumps are not constructed to run submersed..

What makes the pumps in the aquarium trade run submersed is its IP68 electrical insulation.. Taking such a pump out of the water and let it run outside the tank instead doesn't make it run dry... It's running dry if its impeller is running in air instead of water and tthis distroyes the pump..


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## Daveslaney (26 Jun 2016)

The only reason i asked is because when doing research on sump design etc on the net.I have seen some pumps mounted outside the sumps seems like a overcompicated way of doing it to me,So thought they may have some thermal overload circuit to prevent the pump burning out from running dry and thats why they are mounted this way.Think they are just high flow rate,High power pumps though.
You can get pumps with al this inbuit protection,run on controlers etc,But as you say they are very very expensive.
I have used the float style cut offs before on surface skimmer pumps when i had koi ponds and found them to be very unreiable to be honest.
On a correctly sized,correctly maintaned sump i would think there is no more chance of a dry run on the pump than with a canister filter anyways?


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## Chris Jackson (26 Jun 2016)

Yes Marcel I never meant the kind of run dry you describe 

I haven't bothered with any failsafe float switches on mine due to space issues really. In a power failure the sump is big enough to accomodate the drain down from the tank. If the syphon fails on my overflow then I've got problems and the pump will run dry, overheat and create a very minor flood, eeeek, BUT the syphon has to fail in all three of my syphon tubes for that to happen which has to be extremely unlikely....fingers crossed!

With a drilled overflow the chances of an overflow failure must must be considerably less. Still a float switch is a useful backup and when I convert my big tank I'll be including one for sure...


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## zozo (26 Jun 2016)

I've seen pictures here on ukaps from a fellow with a rather large tank running a sump, he made use of a circulation pump which you regularly would find in heating systems.
Pumps like this must be placed outside the sump, then you indeed need to figure out some tubing construction like a syphon to make that work since these pumps are also not self priming you would need to prime it manualy. putting the pump inside the sump prevents this manual priming..

Whit sumps which are not realy for sale anywhere you need to figure out some DIY tubing to make it all work smoothly together.. If you want it all to run perfectly from the start you need to be familiar with math and physics and there are geek formulas to find to compute the tubing sizes needed to equalize pump and drain capacity. Then you need take things in account like, flow restriction of used material, how many bends, diameter, fall speed and pump capacity etc..  If you just go with regular stuf made for an estimated range of capacities like a ready made overflow box suitable for tanks up to 100 gallons then you need to make use of valves to tweak the system to make it run smoothly if you use a smaller volume than those 100 gallons. 

That's actualy another disadvantage of a sump, it's not the use of it, it is the need of having the knowledge to build one that rather runs somewhat smoothly from the start. If you have no clue about basic math, physics and available technical stuff you probably wont know where and with what to begin with.

The risk of a pump running dry increases if the whole system is not in sync.. This can be a rather somewhat tidy process since it works partialy with laws of nature which are not realy constant.. Atmospheric pressure can influence drian speeds of the overflow, or tubes getting dirty over time and restrict waterflow and changing the drain speed. If an overflow gets clogged by dirt, chances for this happening increasy again with the need for use of valves to reduce the drain tube size. So building a sump with estimated specifications always needs some tweaking and fidlling to make it run properly in a constant manner. Since it works with forces of nature which are not always constant it needs constant checking and maintenance to keep working properly.. If you by any chance estimated very correctly with the build of your first sump, you are very lucky..
It's a good practice to build in fail-safes like 2 overflowes, 2 getting cloged at the same time are rather low, but not impossible and a floater switch, 2 failing verflows and a failing floater switch are even more unllikely but not impossible. 

I burnd out a pump recently.. I my case it happened because i miscaculated my overflows and made them to small (took a risk for aesthetic reasons) and if one syphon breakes the other doesn't make up for it. And one night it happened for no obvious reason and the floater switch got stuck for what ever reason, probably a dirt particle.. So i need to rethink my overflow capacity or construct a more reliable floater switch..  sh*t happens.

With a canister which is a closed system it's not likely to trap air.. All tho if you run it high tech with co2 and oxygene bubbles getting sucked a cannister ca trap air and build it up in the sponges.. This also happened to me once and the pump started squeaking.. So now i regularly shake my cannister and hear the trapped gasses come out. Even sometimes i hear it slurp a air bubble out by itself.. But it's not impossible to build up so much it fails to push it through.. As i experienced it once happening.


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## zozo (26 Jun 2016)

Chris Jackson said:


> Yes Marcel I never meant the kind of run dry you describe
> 
> I haven't bothered with any failsafe float switches on mine due to space issues really. In a power failure the sump is big enough to accomodate the drain down from the tank. If the syphon fails on my overflow then I've got problems and the pump will run dry, overheat and create a very minor flood, eeeek, BUT the syphon has to fail in all three of my syphon tubes for that to happen which has to be extremely unlikely....fingers crossed!
> 
> With a drilled overflow the chances of an overflow failure must must be considerably less. Still a float switch is a useful backup and when I convert my big tank I'll be including one for sure...



Indeed with a drilled tank and a good calculated overflow this chances are very small.. I didn't want to drill my tank and use syphons and syphons just are a bit more risky to run.. For floater switches you do not need much room, they come in very small sizes.. I use one of this very small ones.
Or this.. It's sufficient in my case because i run a dc 12 volt pump on a not so large tank, it can take the power. If used with heavier AC 220 pumps it would need an additional relay.


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## Daveslaney (26 Jun 2016)

The float switch i used was along simular lines but made for pond use was called a pump protector or something like that.When i cleaned my main filter,it would drop the water below the skimmer wier.It would do the exact same thing the float would stick the pump would carry on running.In the end i just gave up on it and just turned the pump off with a switch hehe.
I think its the biofilm that develops on the float switch stops it operating.Perhaps aflow switch on the outlet line would be a better safeguard?


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## zozo (26 Jun 2016)

Relying on technical stuff always requires monitoring and maintenance, wear and tear is inevitable.. Beter have spare parts in the house if livestock depends on it.
With building a sump for the first time you always run into thing you might not have tought of till it occurs.. For example if the pumps outflow is under the water surface and the pump stops running the water will syphon back into the sump via the outflow. Is the outflow above the surface you'll hear floatig and splashing water again. So if you place it bellow the surface again make a fail safe to prevent it from syphoning back and flood the sump, do not place it to deep or use a return prevention. I only thought of not hanging it to deep so my sump could take the vulome returnig.. Now one syphon stoped and the sump drained, the floater switch stopped the pump, the pump stopped the water syphoned back into the sump via the outflow and the floater switch got activeted again.. Then you get a constant cycle of switch versus pump.. That was the culprit making my pump burn out.. The switch got activated again every  minute, that 60 times an hour, over several hours the chances only increase it failing just once to switch and damage done pumps running dry and burn out.. Now lesson learned and placed a return valve in the filter outlet tube. Rather obviously what happened and when it happened you think "Why didn't i think of that..

Having a sump is fun, the benefits it has makes up for the extra work and thought's it requires to keep it in check..  It's a great learning curve spreading challanges over different aspects biologically, technically incuding physics and math.. I love it..


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## Chris Jackson (26 Jun 2016)

For the filter outlet I drilled a hole in the return pipe just below the tank water surface, that way water can only syphon back to the sump until this hole draws air and breaks the syphon. Very simple and reliable system with no flow restriction.


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## DavidW (5 Jul 2016)

I'm setting up a sump at the moment. I decided to go with a Herbie Overflow in the tank, which is basically a main drain 6 inches below the surface, and an emergency drain as a backup. The main drain flows into the start of the sump and the emergency runs into the return pump chamber. Having it setup like means that if the main drain becomes blocked you always have the emergency as a backup, so in theory the return pump will never run dry, but in the off chance it does I went for a Jecod DSC-3000 which has a cut off sensor build in if it detects the pump running dry.

I'm putting a non return valve on the tank return which will stop any water syphoning back to the sump if the pump switches off, but they can be a bit on the pricey side, a cheap option is to do what Chris suggested and drill a hole in the return pipe just below the water level.

I'm documenting the build in my thread in the journal section.


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## zozo (5 Jul 2016)

DavidW said:


> I'm putting a non return valve on the tank return which will stop any water syphoning back to the sump if the pump switches off, but they can be a bit on the pricey side, a cheap option is to do what Chris suggested and drill a hole in the return pipe just below the water level.



I use a return valve to, because i just didn't want to drill a hole in the filter outlet, might want to use it again in the future for other builds. But look in the pond shops they probably have cheaper versions of non return valves. The professional ones are indeed a bit pricy but build to hold pressure. 

I got this one for i think it was € 2.50.


 
It has a simple rubber sleave inside, does a good job, doesn't need to hold pressure anyway only a few liter of water.. Can be cleaned very easily when hoses need a clean.


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## DavidW (5 Jul 2016)

That's a great idea. My tank came with a 25mm pressure pipe return from the pump so I've stuck with pressure pipe fitting. I paid about £12.50 for 32mm none return valve and another £1 or so for 32mm to 25mm reducers.

Deciding to go down the path of using pressure pipe has proven to be more expensive than I originally thought. Mainly down to not having anywhere local to get the parts I had to buy online and postage is usually £7.50 to £10 with each order so if you forget to order something it's costly. Even so I'm happy with me decision to go down this route as solvent weld pressure piping if done properly wont fail or leak and looks neat. I've also saved a bit by connecting this to standard waste pipe of the tank return and overflow from the shut off valves using metric to imperial pipe reducers.

If I was to do it again I'd do everything using imperial pressure pipe rather than metric, for some reason the fitting are cheaper.


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## Daveslaney (16 Jul 2016)

As the move has now been put on hold ( long story).
Thought I would make some changes to the tank. Still a bit of a mix of styles. But I think it's getting where I want it to be.


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## Daveslaney (16 Jul 2016)

some buces.


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