Internal Vs External Filter

[xautomaticflowersx]

Hi all. I've been running a Fluval 4+ internal filter in my 30"x12"x16" tank for about 5 years with no problems at all. But I'm sick of all the fiddling around when it comes to cleaning the filter media. Also having a huge black filter on one side of the tank looks pretty horrible to be honest... I'd rather be filling the ground space up with plants!
I've been looking at getting an Eheim classic, as from what I can gather you can't really go wrong with them. However, money's tight right now and I can only really afford the 2213, which is the smaller of the 3 Eheim classics. I've looked at the litres per hour filtration of the Fluval 4+ and the Eheim 2213 and the 2213 is less than half the litres per hour. Even the more powerful Eheim 2217 doesn't have as good l/hr as the Fluval 4+.

Fluval Plus Details

Eheim Classic Details


My questions are these: are these statistics reliable? Would I be better off sticking with my Fluval 4+ from a performance point of view? Are external filters always better than internal despite the l/hr and pump output statistics?

Thanks in advance for any responses.

 

[SuperColey1]

An internal with the same flow rate as an external would be reduced much less when clean as there is no travelling for the
water to do and less media to pass, however due to the smaller amount of media and it being in the tank then it still has to catch the same amount of muck so it gets dirty quicker.

An external also has a huge media capacity in comparison and therefore has the ability to catch more.

I would personally go for a Tetratec EX-1200 (1200lph) seeing as you are wanting plants so you need much higher turnover and you're budget is more likely to stretch to one of them. Should be able to find one brand new for £70 by googling. Comes complete with all the attachments and all the media.

I use the EX700 and can't really fault it.

So in summary a 700lph internal will beat a 700lph external for flow around the tank BUT it will get clogged much quicker and has much less the capacity for media. It also takes up space etc.

AC

 

[shroob]

Your tanks only 94 litres so I think a tetratec EX1200 would probably be overkill and the current created by the filter abit too much.

I prefer externals simply due to the fact it free's up tank space and doesn't look intrusive (much why you don't like your fluval 4+), an intake tube is alot easier to mask than a big box.
If money is tight I would look around ebay or your local free ads paper, I've had some deals from there in the past.

Like Super said, externals generally hold alot more media than internals and theres more than just flow rate that determines the effectiveness of a filter, I'd go on peoples recommendations and reviews of a filter over the claimed technical stats when chosing a filter to buy.

Both filters would do the job, so its really a matter of personal preference.

 

[raptorrex]

Hi all. I've been running a Fluval 4+ internal filter in my 30"x12"x16" tank for about 5 years with no problems at all. But I'm sick of all the fiddling around when it comes to cleaning the filter media. Also having a huge black filter on one side of the tank looks pretty horrible to be honest... I'd rather be filling the ground space up with plants!
I've been looking at getting an Eheim classic, as from what I can gather you can't really go wrong with them. However, money's tight right now and I can only really afford the 2213, which is the smaller of the 3 Eheim classics. I've looked at the litres per hour filtration of the Fluval 4+ and the Eheim 2213 and the 2213 is less than half the litres per hour. Even the more powerful Eheim 2217 doesn't have as good l/hr as the Fluval 4+.

Fluval Plus Details

Eheim Classic Details


My questions are these: are these statistics reliable? Would I be better off sticking with my Fluval 4+ from a performance point of view? Are external filters always better than internal despite the l/hr and pump output statistics?

Thanks in advance for any responses.

my first advice, don't believe the claims of the manufacturer on a filters pump capacity. one of the reasons Eheims seem to have a lower flow rate, is they are more honest about the "actual" flow, than other manufacturers. (how much more honest, is open to debate).

I feel Externals have three major advantages over an internal:

1, they get clutter out of your tank, avoiding the need to mess around in the tank when cleaning. and, in my case, reduced cleaning from every two weeks (internal). to every six months(external)

2, they have, usually, a much higher capacity (media) than a internal.

3, often overlooked, the time the water is in contact with the media. though there are differing opinions over, just, how long this contact should be. consensus seems to number it in minutes not seconds.

 

[xautomaticflowersx]

Thanks to everyone for the advice. I'll take a look on ebay for the filter you suggested SuperColey1, maybe I'll be able to pick up a bargain!
shroob I appreciate your opinion regarding the flow rate being overkill on such a small tank, however the Fluval 4+ is supposed to be 1000l/h and I've never found that the current in the tank has been excessive, especially when you have a spray bar. Plus I prefer over-filtration for peace of mind... if I miss a water change I don't have to freak out about water quality. Though obviously I realise that over-filtration is not a substitute for water changes.
Thanks also to boboboy for your input about the advantages of external filtration.

 

[SuperColey1]

Your tanks only 94 litres so I think a tetratec EX1200 would probably be overkill and the current created by the filter abit too much.

Not in a planted tank!!! 10x volume is the suggested aim these days I am on 17x and others as much as 30x. No probs with the fish. You have to remember that the plants break the flow and therefore with standard 'suggested' rates the flow will not distribute nutrient and CO2 around the tank properly.

one of the reasons Eheims seem to have a lower flow rate, is they are more honest about the "actual" flow, than other manufacturers.

Eheim are just as optimistic with their ratings as everyone else is. The reason flow rates are higher on the cannisters than you get in your tank is this is the maximum the powerhead can achieve.

Someone on another forum I use tested an Eheim's actual lph on their tank when connected and filled with media against a Tetratec of equal quoted lph. The Eheim result was 54% of the manufacturer's claim whereas the Tetratec was 51%.

The manufacturers just tell you how powerful the powerhead is. They can't give actual figures for with media and hoses etc because they don't know what media each person will use, how long the user needs their hose, what attachments the user will use etc.

Its pretty safe to assume that when you buy a 700lph external that it will be running much closer to 350lp in real terms whereas a 700lph internal will be much closer to its stated flow (of course assuming they are clean)

Easy to test by eye really. Put an internal in a tank and watch. Then put the external outlet in the same place. They may both be the same max lph but the internal will look much much more.

AC

 

[raptorrex]

Eheim are just as optimistic with their ratings as everyone else is. The reason flow rates are higher on the cannisters than you get in your tank is this is the maximum the powerhead can achieve.

Someone on another forum I use tested an Eheim's actual lph on their tank when connected and filled with media against a Tetratec of equal quoted lph. The Eheim result was 54% of the manufacturer's claim whereas the Tetratec was 51%.

after a thread on this forum, we contacted, Eheim, Fluval/Hagen and Hydor, to find just how they measure their cannister flow rates.

Eheim do their test with a full set of "recommended" media 50cm of pipe on each side. ( i use the recommended media, as do many others). they also give a head flow rate and a filter flow rate. they do not, and as far as i can find never have, rated their filters by the Power of the pump alone.

Hagen do theirs with no media and pipes of an undisclosed, but equal length.

Tetratech do their test with no media, and 1m of pipes

Hydor test with the supplied media (sponge and floss) and 1m of pipe.

I did contact Interpet, but they claim not to sell a cannister!!!!

as you see above, whilst you may quible about the "actual" figures. The Eheim method is far more representitive of the "true" flow rate of the filter.

different media combinations will effect flow more or less, but at least Hydor and Eheim put some in for their tests.

 

[SuperColey1]

I think the manufacturers are having you on a bit here!!!

These were the 2 filters run in the test I talk about and they were both brand new at the time with 1.5m on each hose from powerhead to inlet/outlet attachments:

Tetratec EX1200 with recommended media and supplied attachments
Stated lph 1200lph
Actual lph 500lph - 42%

Eheim 2080 with recommended media and supplied attachments
Stated lph 1700lph
Actual lph 800lph - 47%

The Tetratec's attachment include square angled connectors to go over the tank and when these were replaced by rounded ones like the Eheim have the lph increased to 560lph which is 47% (The same as the Eheim!!!)

Therefore I think you can assume that all these manufacturers are stating the powerhead's max performance or:

-They are lying
-The attachments plus the extra hose halves the performance

If Eheim are giving a lower lph because they are 'more honest' then this reduces the % efficiency in comparison to their competitors.

In the test the Eheim was a lot quieter though so that is one bonus for the Eheim owner's club at least.


This flow reduction (in all brands) is one factor in the reasoning why we now use 10x or more lph than volume on our planted tanks!!! Because the actual flow of these filters just doesn't circulate the water enough in a tank where there are many obstacles (plants/hardscape) etc.

Those of us who already assumed our filters were going to have enough flow for our use are adding Powerheads (mainly the Koralia series) to superboost the circulation due to most filter manufacturer's exaggerations!!!

I personally have a Tetratex EX700 (tested at 325lph) plus a Koralia1 which is 1500lph in my 125ltr tank!!! (17x by stated lph)

AC

 

[Schmill]

Only because it was one manufacturer that wasn't mentioned in the above list, Aqua One actually quote 2 figures on their filter specs.

I have the Aquis 1200 and it says the following:

Operating Flow Rate*: 750 LPH
Maximum Flow Rate**: 1100 LPH

*Operating flow rates are based on a typical setup with the cannister placed under the aquarium, complete with filter media, pumping to a head-height of 120cm not including spray bar or duckbill attachments.
** Maximum flow rates are based on measurements taken as the water exits the filter unit when it is positioned next to the aquarium with no filter media in the cannister

They get bonus points from me purely because, like Eheim, they are giving you a 'real world' figure as well as their nice high 'marketing figure', and they explain how each of them was achieved.

 

[raptorrex]

I think the manufacturers are having you on a bit here!!!

you mean they are not doing things the way they say as none of my post deals with actual figures, just exactly what are the manufacturers using wool to hide?

As for a "test" on another forum. it is no more valid than an opinion. unless the test is monitored, by a independent source, the results can be no more than hear say. that is not to say the figures are wrong, mealy to point out that they have no more validity than the claims of the manufacturers.

thanks to Schmill for the comments from Aquis on the Aqua one. it was not one of the manufacturers we polled. nice to know that there is another manufacturer that puts "real" media in for tests.

 

[SuperColey1]

I think the manufacturers are having you on a bit here!!!

you mean they are not doing things the way they say as none of my post deals with actual figures, just exactly what are the manufacturers using wool to hide?

As for a "test" on another forum. it is no more valid than an opinion. unless the test is monitored, by a independent source, the results can be no more than hear say. that is not to say the figures are wrong, mealy to point out that they have no more validity than the claims of the manufacturers.

thanks to Schmill for the comments from Aquis on the Aqua one. it was not one of the manufacturers we polled. nice to know that there is another manufacturer that puts "real" media in for tests.

I don't for a minute suggest that it is a test that should be taken as gospel but it is a pretty good indicator.

Eheim testing a filter flow rate with the media and 5cm of hose is ridiculous!!! For someone to give a filter flow rate they need to use a decent amount of hose (as the Aqua One does) and then both of them need to use an outlet of some type (the one they provide with the filter I would suggest) and this is the filter flow rate. Not adding a teeny bit of hose and turning the filter on!!.

I tested my EX700 @ 325 with recommended media, their supplied attachments (which I don't use) and my tank uses approx 1m hose each side with their attachments. So in theory without the attachments restricting flow this rate could be significantly more. I know it would be more but not by a huge amount!!!

I think I will do some more research into this to satisfy myself I am not going mad. lol

AC

 

[raptorrex]

I think the manufacturers are having you on a bit here!!!

you mean they are not doing things the way they say as none of my post deals with actual figures, just exactly what are the manufacturers using wool to hide?

As for a "test" on another forum. it is no more valid than an opinion. unless the test is monitored, by a independent source, the results can be no more than hear say. that is not to say the figures are wrong, mealy to point out that they have no more validity than the claims of the manufacturers.

thanks to Schmill for the comments from Aquis on the Aqua one. it was not one of the manufacturers we polled. nice to know that there is another manufacturer that puts "real" media in for tests.

I don't for a minute suggest that it is a test that should be taken as gospel but it is a pretty good indicator.

Eheim testing a filter flow rate with the media and 5cm of hose is ridiculous!!! For someone to give a filter flow rate they need to use a decent amount of hose (as the Aqua One does) and then both of them need to use an outlet of some type (the one they provide with the filter I would suggest) and this is the filter flow rate. Not adding a teeny bit of hose and turning the filter on!!.

I tested my EX700 @ 325 with recommended media, their supplied attachments (which I don't use) and my tank uses approx 1m hose each side with their attachments. So in theory without the attachments restricting flow this rate could be significantly more. I know it would be more but not by a huge amount!!!

I think I will do some more research into this to satisfy myself I am not going mad. lol

AC

oops sorry a typo its 50cm, on each side which is 1m total, the same as the others, who use hose. I'm fairly sure using no/little pipe will give you a lower turnover than using pipe, as part of the flow is made up through the syphon effect, caused by the water flowing into the filter. not absolutely sure on this, but it makes sense.

 

[Schmill]

Unless it tells you what 'head' the filter was pumping to then the length of pipe is a bit meaningless...

I could have an 2m inflow pipe to a sealed container from a tank 1.8m above it, and a 2m outflow pipe from the sealed container and laid across the floor. Once the syphon action started there would be a flow.
Using exactly the same setup but having BOTH pipes up to the tank 1.8m above there would be no flow, (no syphon action).

Similarly if you included a pump in the 'sealed container' (starting to sound like a cannister filter to anyone? ), then again with the outflow pipe laid across the floor, (and the inflow pipe if you like), you are going to be getting better flow than when you have those 2 pipes travelling up 1.8m to the tank.

I hope that makes some kind of sense

 

[raptorrex]

Unless it tells you what 'head' the filter was pumping to then the length of pipe is a bit meaningless...

I could have an 2m inflow pipe to a sealed container from a tank 1.8m above it, and a 2m outflow pipe from the sealed container and laid across the floor. Once the syphon action started there would be a flow.
Using exactly the same setup but having BOTH pipes up to the tank 1.8m above there would be no flow, (no syphon action).

Similarly if you included a pump in the 'sealed container' (starting to sound like a cannister filter to anyone? ), then again with the outflow pipe laid across the floor, (and the inflow pipe if you like), you are going to be getting better flow than when you have those 2 pipes travelling up 1.8m to the tank.

I hope that makes some kind of sense

so having, no or a very short pipe would not allow the syphon to start. but i imagine a short outlet pipe, would aid flow. as the water weight pushed out would be less.

 

[OldMan47]

Sorry to burst your bubble Schmill, as long as the supply and return are to the same tank the height only matters in one place. That place where it matters is not the pumping rate but the NPSH, net positive suction head, that the impeller sees. The suction and discharge going to the same height means that any force needed to raise the water to a particular height will be supplied by the suction head. The only effect that the height has on flow is the length of hose it will take to reach that far. If the NPSH is adequate for the impeller, it will also not affect pumping rate. NPSH is the reason that filter manufacturers tell you how far below the tank water level to mount the filter. If it is inadequate, it will interfere with proper operation of the pumping mechanism, the impeller. It is called net positive suction head because it is the suction head available to the impeller above the saturation pressure at the existing temperature. In a very hot system, completely different than what we see in an aquarium, it may take a lot of pressure to keep the water from boiling. That pressure is subtracted out to get the net.