canister filter

[ac7av]

NO canister filter is going to denitrify.

Don

I curious as to how you came to that conclusion? All denitraters available on the market and DIY units all get the same water out of the tank. Some require feeding them directly. None of them have a special requirement that says low oxygenated water only into the unit to work that I’m aware of. Look everyone knows you can not just hook it up and expect it to work now. Like any tank, it requires cycling. The filter floss and debris that gets trapped in it will cause a cycle just like any tank. You can put a canister filter on a tank with no rock and glass marbles for looks on the bottom and it will after a while, when it cycles and balances reduce nitrates like rock, like sand, like any denitrater will, after it cycles. I would be happy to do an experiment with a tank, fish, non pours granite rocks so the fish have something to claim as there own space. The problem with this is the time it takes. Kind of like cycling a tank it just takes a bit longer.

 

[Krish]

You can put a canister filter on a tank with no rock and glass marbles for looks on the bottom and it will after a while, when it cycles and balances reduce nitrates like rock, like sand, like any denitrater will, after it cycles.

I don't think it will balance out because I can't think of anywhere in a system like that where denitrification would take place so there could never really be a balance so to speak that would last . In order for denitrification to take place, you have to have an environment void of oxygen. A tank with no live rock or that doesn't have a deep sand bed (which to add only the lowest portion of a dsb can provide denitrification) your nitrates will just continue to rise unless you do constant water changes to try dilute the nitrates. The only other thing I could think of that will help in a system like that to keep nitrates down would be the algae that will result from the high levels of nitrates using some of the nitrates for it's growth. However, who wants a tank full of nuicance algae?? A canister filter won't provide you with any denitrification and if it could by some miracle, it would provide you with so little that you wouldn't even see a drop in nitrates using one. This is why liverock is so important to a tank. On the outer portions of the rock aerobic bacteria colonizes and performs the simple task of converting ammonia into to nitrite and nitrite into nitrate then deep within the rock, there are zones void of oxyen that denitrification takes place. This environment cannot be found in a canister filter. Just think of it...If it were that easy, everyone would be running a canister filter and would say to hell with all the skimmers, fuges, live rock etc. As for those denitrators you see on the market, I think they are a waste of money too which is why you don't see anyone using them.


I'll give Don a chance to chime in, but please keep in mind that I am not trying to knock you down Erick and say that I am right and you are wrong because I am far from that kind of person. I've been around this forum for years now, saw many debates on similar subjects along with the knowledge I've learned and quite honestly, not sure if you will find one person here who would ditch their live rock and all other forms of filtration and rely only on a canister filter to do all the work for them. It may look like it is working for you in the beginning as the tank completes the initial cycle which it would, but give it a bit of time and you will just watch your nitrates climb higher and higher. Guess we'll wait for the others to chime in. Once again don't think I am knocking you down or trying to be rude. Nothing more than a friendly debate which we can all learn from (myself included)

 

[ac7av]

Hey
Now worries.
I would never think your or Don were trying to put any body down. It’s always hard to here the intended meaning when reading. I think that’s where a lot off conflict happens so I always keep an open mind about what I’m reading.

I know there is and will always be a lot of talk about canister filters not belonging in marine aquariums but the fact is they do work, and many use them. If I had an extra one I would start an experiment tomorrow and list the test results weekly for 6 months but currently the one I have is being used for carbon. I think you and others just assume that there are no low flow, low oxygen environments in the canister and I think simply because of the shape of most canister filters it is favorable for a large percentage of the filter environment to be capable of denitrating. It may help if you think of it more like live rock turned inside out. You talk about the rock from the out side in, I believe the canister fully loaded works like the rock inside out. The majority of the water flow is threw the middle of the filter and much slower as you get to the outer walls of the filter. Look at it another way. The filter media could be anything that is porous to act like live rock too. A sponge, those ceramic rings, bio balls, who said you couldn’t put rock rubble in the filter. So for example, if one filled the canister with rock then why would it not be able to remove nitrates? What does the box it’s in, have to do with its ability? Does it have to be in an open top tank to work?

 

[returnofsid]

All denitraters available on the market and DIY units all get the same water out of the tank. Some require feeding them directly. None of them have a special requirement that says low oxygenated water only into the unit to work that I’m aware of.

It's not about "low oxygenated water," it's about low oxygenated media. The bacteria that "eat" nitrates, do not thrive, in a well oxygenated environment. The bacteria responsible for Denitrification requires an anoxic environment. This is similar to Crushed Coral vs. Aragonite sand. Water is more able to flow through CC, due to the larger particle size of the media. Because of this, you'd need a much deeper bed of CC, than you would of Aragonite sand, to still create an anoxic (low oxygen) and anaerobic (little or no oxygen) environment. This is also why DSB (Deep Sand Beds) in our refugiums are recommended. A 1" sand bed, in our display tank, is not deep enough to create the proper environment, for denitrification to occur. We make up for this by creating the proper environment, by the use of a DSB in the refugium.

On of the best "Denitrification devices" involves a 5 gallon bucket 2/3s full of aragonite sand, with water SLOWLY moving through it, before returning back to the display. This is typically referred to as a Remote Deep Sand Bed. It was originally used, and brought to our hobby's attention, by Anthony Calfo.

Canister Filter, Wet/Dry Filters, Bio Balls, etc. all do a great job of converting and breaking down ammonia. Unfortunately, they're useless for breaking down nitrates, since they are an aerobic environment.

Here's a few excellent articles, that explain this in more depth, and may help us understand.

http://reefkeeping.com/issues/2008-04/newbie/index.php

Here's a great one. I've copied and pasted a couple of important paragraphs, that explain it, in a pretty easily understood way.

http://reefkeeping.com/issues/2008-05/newbie/index.php

"Beds need to be deep enough so that zones are created in the bed. The upper levels have decreasing oxygen tension, and organic compounds are processed by aerobic bacteria. Lower in the bed, oxygen approaches near depletion and bacteria use the oxygen contained in the nitrates, produced at the upper levels, to further degrade organics but using the oxygen from the nitrate molecule. This anoxic zone is where denitrification occurs and is the main reason for having a DSB in the first place. Four inches is the suggested depth, but having slightly less usually doesn’t hurt. Extremely deep beds, on the other had, run the danger of becoming fully anaerobic at their lower levels. That is not an ideal condition and should be avoided. Even at 4-6” there are some anaerobic areas in any sand bed, but those over 10” are more likely to have substantial zones. This invites conditions where sulfates can be reduced to toxic hydrogen sulfide.

One of the necessary conditions for a bed to be successful is that it has a continuous turnover caused by sand-shifting organisms in the bed. This means that sand should be fine enough for these organisms to move about. Very fine sand can actually be moved around by the combined efforts of the bacteria in the bio-film on the sand. The other reason for fine grains is that they provide a far larger surface area than large grains, thereby supporting greater organic loading. Having sugar-fine sand or finer is therefore far better than having something, like crushed coral, for the bed.

As I explained above, it is desirable to have zones of decreasing oxygen tension existing in the bed. It takes time for these zones to develop, so we want to keep them intact. Adding large sea cucumbers, large burrowing fish or big starfish, which can all disturb the bed, should be avoided. So should using one of those sand vacuums, so popular for cleaning substrate in a freshwater tank; they should be avoided unless it is just used to clean the very top of the bed."

Finally, here's another great article, part of which contains the following, which I also copied and pasted here.

http://reefkeeping.com/issues/2002-06/dw/index.php


"Like live rock, sand also works as an excellent denitrification filter when a bed of four or more inches of sand is used.Sand is so efficient that denitrification can even occur on a single grain of sand."

In the same way that we need a deep sand bed, to create anoxic and anaerobic environments, while Live Rock does help, with denitrification, the majority of it occurs deep within the rock, instead of on the surface.

 

[ac7av]

No one is in dispute that sand and rock form the base for nitrate removale in the aquariums we keep. So a 5 gallon bucket is some how different then a canister filter full of the same?

 

[returnofsid]

No one is in dispute that sand and rock form the base for nitrate removale in the aquariums we keep. So a 5 gallon bucket is some how different then a canister filter full of the same?

Actually, yes. In a canister filter, it'd be impossible to create an anoxic and anaerobic environment, which is necessary for denitrification to take place.

To create such an environment, requires a deep enough substrate, of small enough particles, that it limits the amount of oxygen that can penetrate.

Filling a canister filter with 4-6" of fine sand would destroy the canister filter.

Rubble rock, bio balls, ceramic rings, etc. won't inhibit oxygen penetration, thus they can't create an anoxic or anaerobic environment.

 

[Krish]

The filter media could be anything that is porous to act like live rock too. A sponge, those ceramic rings, bio balls, who said you couldn’t put rock rubble in the filter

Good thought! However, the size rock (or should I say rubble) that would fit into a canister filter would be really small pieces that wouldn't have enough mass to provide you with any denitrification to talk about much less any at all. Same thing with bioballs, but they are even worse. All a bio-ball is, is a ball with alot of surface area for nitrifying bacteria to grow and nothing more. There are no anaerobic zones inside of a bio-ball. Also, I see where you are coming from with putting enough sand in a canister filter to create a deep sand bed where denitrification could work which is very logical, but could you imagine what would happen to that canister filter if you plugged it in with all that sand?? :shock: It probably would burn up. Shucks, if you leave the sponge in there too long before cleaning it that alone almost prohibits flow. But let's just say flow was allowed to pass through it...With flow coming from the center out as you suggested, you'd probably have a sand storm in there which will cancel out there be any anaerobic zones and also, you would be transferring milky sandy water into your main display from all the churned up sand. IMO, for you to be able to use a canister filter for denitrification you would need a really really big canister filter (one that I've never even seen on the market LOL) that could hold big pieces of live rock that can actually perform denitrification.

Just a few personal thoughts of my own.

Hey
Now worries.
I would never think your or Don were trying to put any body down.

Really good to know. I would never post here to try and make someone feel like an idiot or put anyone down as I don't know it all and I'm still learning myself plus in general, I'm not that kind of person. Good debates are great as everyone gets a chance to learn something in a civil manner

 

[Scooterman]

So I guess a simple point of a canister failing would be lack of proper surface area, particle size required to produce aerobic and anaerobic zones, so it ends up dumping back everything it does into the tank?

How does that sound?

 

[ac7av]

I’m starting to feel that it’s the size that’s throwing you off track.
Sand is not going to damage a canister filter, at least not the one I have anyway.
You are not going to get a sand storm in the canister filter, there is simply not enough water flow.
I could put easily 30lb of the same pours lava rock in this canister that I use in my display tank and I know it will do the job.
A lot of peoples refrugiums are smaller capacity then a canister filter.
And again with the 5 gallon bucket, what’s the difference, just because the canister has 6 sides and a pump built in means it will not do the same job as a remote DSB made out of a 5 gallon bucket? I just don’t see the logic in that one at all. If we are talking about a 125 gallon system then I mite agree that the canister is not big enough. But we are not really talking about tank size, just can it do it.

Let me make another example to try and clear it up. Lets use regular material that anyone mite put in there refrugium, in to the canister for GP. I measured the canister I have and it is 9 X 9 X 16 inches. Lets lay it on its side and cut the top off. Now with that same 4 to 6 inch sand bed and the 100 gallons an hour or so of the built in pump running why is this not able to denitrate? What does it matter if its standing up or laying on its side to work, if it’s the position then lay it on its side. You done and done.

 

[DonW]

I curious as to how you came to that conclusion? All denitraters available on the market and DIY units all get the same water out of the tank.

Well your comparing apples to oranges. First the canister filters flow is way to fast, comparing it to a denitrating device is well a very poor comparison. There is no denitrification to speak of in a canister filter no matter how long it cycles. A denitrator flows at such a slow pace the o2 is consumed and this is what makes it a denitrating device.
I'll add that inside a denitrating device the 02 is so low th ph is acidic meaning low and most times low enough to consume calcium reactor media. I mention this because it give you an idea of what is going on inside your LR. These low/no 02 zones are the only place that denitrification happens.



Don

 

[ac7av]

I think your missing what I just said. Flow is not the issue, if it was, we would all want much less flow threw our refrugiums that a lot of the time have deep sand beads of 4 to 6 inches. Canister filters do not have a lot of flow. What, are they like 100 to 200 gph at best. Its not like the thing has 1000 gallons of water going threw it like many peoples refrugiums. I would not be pushing so much on this if I had not been there and done it and tested it. I didn’t go out to do it but it was something I stumbled onto. Yes it does take a bit longer using a canister filter to “cycle” the tank. This is the main reason I believe that they have a bad rep for becoming nitrate factories. I don’t know why it is that it takes longer to cycle, but I have a theory about it. I’m just having a hard time understanding why many people think it will not work and the only reason I can think of is because its called a canister and not a sump or bio box or refrugium, or what ever other name you want to call it. The fact is you can put anything in a “canister” you want and much of the stuff you could put into a refrugium will also work in a canister filter in the same way it will work in the refrugium. The physics of the material doesn’t change some how by putting it in the canister. If you just try and think of it as a container and nothing more it becomes clearer how un different it is to a number of other devises we use for nitrate removal. Everyone likes to put valves on everything to adjust flow and is there some reason you can not do that to a canister? If you’re just stuck on the flow aspect of it then just try this. If you think it need less flow use a valve. Heck my cheep flea bay filter came with 2. Dial it down to your liking and watch it work. It really can’t get much simpler then that to address the flow issue and its not like you have changed the canister into something its not by doing so.

 

[vimal]

great thread!! with good info!!well,so do you guys thinks canisters work well for saltwater tank?i got a canister filter with level of adding,hmm,any suggestion for these addings?

 

[DonW]

I think your missing what I just said. Flow is not the issue,

Sorry but that is just plain not accurate. Flow is a what it is all about even at 200gph. In order to denitrify the flow would have to be slowed to a steady drip, that woud destroy the filter pump. Denitrifing devices run in ml per minute not gph.
We talk about o2 and some are missing that the water carries the o2 it not atmospheric exsposure. The flow has to be so slow that the o2 is consumed by bacteria that are creating the nitrates. This gives a zone for denitrifying bacteria. It works just like a dsb, LR or anything else. Bottom line canister filters have way to much o2 just like bio balls or anything else to denitrify at any efficient pace.

Don

 

[Krish]

Sorry but that is just plain not accurate. Flow is a what it is all about even at 200gph. In order to denitrify the flow would have to be slowed to a steady drip, that woud destroy the filter pump. Denitrifing devices run in ml per minute not gph.
We talk about o2 and some are missing that the water carries the o2 it not atmospheric exsposure. The flow has to be so slow that the o2 is consumed by bacteria that are creating the nitrates. This gives a zone for denitrifying bacteria. It works just like a dsb, LR or anything else. Bottom line canister filters have way to much o2 just like bio balls or anything else to denitrify at any efficient pace.

Don

Nicely put Don. I was surprised to see this debate still going! I have been away and just got back a few mins ago. I guess eventually it wil come down to people doing what they want or feel works for them.

 

[ac7av]

Well I guess were just going to have to agree to disagree on this one. I have no doubt that canister filters are not used much these days with other advancements and understandings of the bacterial profile required to have a balanced system. A canister filter can be a complete biological filtration device for a tank in the same way that any refrutium with hundreds of gallons of water per hour, not drips per minute running threw them. I don’t see too many people running the drip count into the pile of live rock or live sand in there refrugiums. Understanding how to make that happen is certainly a discussion and a half. As you have pointed out several times, it’s the media doing the work but some how you don’t believe the same media in a canister filter works the same way as it does in a bucket or other container. I get the flow thing and O2 thing but it just simply doesn’t hold water in my opinion.

As soon as I can come up with something else to put carbon in for my main tank I am going to start some experiments with my canister filter to see what different materials in it will do to water quality and testing result levels. I just have to see again for my self and for others that pop up on the site asking about canister filters and everyone just says dump it in the garbage immediately. I’m convinced that may people that say that have never used one themselves and they just jump on the band wagon.

 

[Krish]

A canister filter can be a complete biological filtration device for a tank in the same way that any refrutium with hundreds of gallons of water per hour, not drips per minute running threw them. I don’t see too many people running the drip count into the pile of live rock or live sand in there refrugiums

You are right that the flow in a canister is slow compared to a tank. Infact, live rock in a tank probably gets 10 times the flow rate than rock in a canister filter would, but the difference is the rock itself...Atleast IMO. You are not going to be able to put more than rubble in a canister filter (atleast all I've seen on the market) but in a tank, you have more quantity of larger pieces that deep inside of which, you will have anaerobic zones for denitrification to take place (regardless of what flow you have on the outside of the rock). You think of a canister filter, all you would be able to fit in there is rubble which will act like any other media or bio-ball out there which is good for nothing more than breaking down waste to the point of producing nitrates and stop there. Not enough mass to have anaerobic zones or anything to talk about. As for sumps and refugiums, IMO, them alone can't do the trick either unless you have a big enough sump/fuge to hold enough rock to do the trick which will be the same case for a canister filter as it would have to be really really big. When people say that have a 90 gal tank with a 20 gal sump where only 10 gal of it has liverock in it and they think that is completely taking care of their biological needs, they are sadly mistaken It is the rock in their tank doing all the work and that is just a bit extra/bonus rock to help out which usually in that case does more harm than good when the rock just sheds and traps detritus.

Anyways, that it just my thoughts and understanding of it all which can be completely off target. It will be good to do your test! Let us know if you do it

 

[DonW]

I get the flow thing and O2 thing but it just simply doesn’t hold water in my opinion.

Its not a matter of opinion. Its a matter of fact and science. You compare a denitrating device to that of a canister filter. Denitrating devices are based on very low flow just like LR and a DSB, not opinion but fact.

This is a quote from the product manual concerning flow rate for probably the most popular and best denitrifier on the market, Midwest Auatic.

"The unit should be run for 3 days at 1 drop per second.
Then the drip rate can be increased to 2-3 (3-6 for XL unit) drops per second"

Thus why it works vs not. LR and a DSB work exactly the same way. A canister filter is not a complete filtration solution.

Don

 

[ac7av]

Krish
The point I was making was that you can just put anything you want in the canister filter, not that all the different things will remove nitrates. Yes when I start the tests It will be with bare bottom tanks with only live stock in them. And some non pours material for the fish to hide in and feel safe.

Don
I know it’s not a matter of opinion, it’s a matter of fact and science. My opinion is that you’re forgetting that fact and science still do not change simply because of the box it is in. I believe fact and science work the same no matter where it is. I also agree that many have refrugiums that are way to small my self included at this moment. I think that the same thing happens with the use of canister filters. If there not sized correctly neither will work as the complete filtrations for a tank.

I am not going to be doing this test using a canister filter and a 200 gallon tank just because it says it will work on a tank that big. As all things in this hobby they too are way over rated, like skimmers, UV filters, and what ever else comes with a tank size rating. I believe because of the size of the filter that a 20 or 30 gallon tank will be a good match and many people have tanks this size and I just happen to have a couple of extra ones at the moment.

I’m not going to try and change the test results for my own benefit to prove my point. If it doesn’t work out then I will list the results accurately to help the community. I just believe that the science will prove it all works the same not matter where or what it’s in.

 

[returnofsid]

To make this an actual "Scientific Experiment," comparing Canister Filters to other denitrification systems, you'll need to set up several tanks, with identical livestock, identical feeding regimes, identical maintenance, identical flow....etc. The tanks will all have to be identical, except for the various denitrifying systems. You'll also want to set up a tank with absolutely no denitrifying system.

The thing with flow is this:

In a good canister filter, all of the water flow is "forced" through the media, at whatever gph the canister is designed for. That's how they're designed and that's why they're so good at what they're designed for. Throttling down a canister filter will destroy the motor. Some canister filters do allow you to adjust the flow, slightly, but nowhere near as low as would be needed.

In a refugium, with a deep sand bed, even if hundreds of GPH of flow is flowing through the refugium, it isn't all flowing through the deep sand bed. Water will take the "path of least resistance," if allowed. A Canister filter doesn't allow this, because that's not how they're designed to work. In a refugium, while there may be a lot of water flowing through it, very little water is flowing through the deeper areas of the sand bed. As you get deeper into the sand bed, less water flows through it, allowing time for the bacteria, in the anoxic and anaerobic areas, to "eat" the nitrates. In a sense, in a deep sand bed, the water "percolates" through the media, as apposed to actually "flowing" through the media.

 

[DonW]

Krish
The point I was making was that you can just put anything you want in the canister filter, not that all the different things will remove nitrates. Yes when I start the tests It will be with bare bottom tanks with only live stock in them. And some non pours material for the fish to hide in and feel safe.

Don
I know it’s not a matter of opinion, it’s a matter of fact and science. My opinion is that you’re forgetting that fact and science still do not change simply because of the box it is in. I believe fact and science work the same no matter where it is.

Your right that the container doesnt matter but your not understanding the science and facts. Its just that simple, I understand your line of thinking but its way off. It does matter how much flow you have and what the denitritying bacteria have to feed on.

You could with a valve feed a canister filter full of LR 3 drips per second and it would denitrify until it built up so much sulphide gas that it crashed the tank. Not to mention the LR would dissolve due to the low ph.

Or you could fill it with LR and run at its typical 200 gph. It would trap detritus and food. While the 200 gph oxygenated water fed the nitrifying bacteria creating a nitrate factory.

This isnt anything new and is very basic reef chemistry. Its been proven many times year after year for decades.

Don