Filter Rates & Flows

[Metka]

Hi everyone! 

 
Lunar Jetman and I are embarking on a mission - a mission to uncover the truth behind inflated manufacturer's filter flow rate statements.
 
Almost all filters available on the market will have a specified "flow rate", how much water can physically be pumped through the system. Usually these are measured in LPH (litres per hour) or GPH (gallons per hour).
 
Generally, these figures are somewhat incorrect. The manufacturer obtains these numbers by running the filter EMPTY, with very short intake/outtake tubes and with NO FILTER MEDIA. This causes the flow rate figures to be (in some cases) hugely overstated.
 
What we're asking of you, is to provide a true real-time capture of the flow rate of your filters. Using this data, we can then build an accurate picture of the truth behind the statements, eventually building a go-to-guide for everything filter related. ALL BUILT ON FACTS, not estimates.
 
We welcome your thoughts, queries, comments and questions on this subject, so please get involved and help out anyway you can.
 
To obtain your true filter flowrate, it couldn't be easier. Follow these simple steps:
 

1. Grab a bucket, large enough to hold 15 seconds of your filter water.
2. Weigh the bucket empty.
3. Capture 15 seconds of water that flows out of your filter, in the bucket.
4. Weigh the now filled bucket.
5. Water is pretty much exactly 1kg = 1litre. Thus, if you had 3kg of water after 15 seconds you captured 3 litres of water.
6. Do the simple mathematics to work out the hourly rate. In this case, as we've captures 15 seconds - times it by 4 to get the minute figure - then times it by 60 for the hourly rate.
 
This will give you your actual through-put of waterflow for an hour.
 

 
 
I'll start things off by providing a set of data of the current filters I have in my possession:
 
 

Filter Brand & Model: Aquamanta EFX400
 

Link: http/fishkeeper.co.uk/site/product/aquamanta-efx-400-external-filter-
Stated Flowrate: upto 1400 LPH
Suitable Tank:  upto 400 Litres
 
Contributing factors:
Age of Filter/Filter Media:  Around 6 months old from NEW.
Media Used:  All standard media that comes with the filter - minus the carbon bags. 
Filter Position:  Directly under the tank, about 1 meter from top of water level.
Tubes:  No kinks, cut to size so as to be taught, but with enough wiggle room for access to filter. I will measure each tube length when I get home.
 
Actual Flowrate:  478 LPH
Filter Flowrate Rating: 34.14%

 

[daizeUK]

You will probably want to explain how you measured the actual flowrate.

 

[Metka]

You will probably want to explain how you measured the actual flowrate.

Thanks for that. I have added it to the main topic.

 

[MojoDex]

Now this could be very interesting. Do you want the filter cleaning before tests or not?

 

[Metka]

Now this could be very interesting. Do you want the filter cleaning before tests or not?

I would say yes, clean them first - lets give the filters a "best case scenario". Once we have this data, we can they begin to capture the flowrates of ageing filters/filter media.

 

[baker360360]

im up for this, will have a go when doing my next water change  

 

[mhancock]

will be interested to follow this thread!

 

[TwoTankAmin]

IMO there is not good way to compare flow rates except w/o any media. Otherwise one must use standard media loads and test them 1005 clean. After that you change results to much to be useful. But then media volume is more important than flow rate when it comes to filtration and dwell time is important too.
 
Using too large a filter with the flow rate turned down is better than a smaller filer at a higher flow rate.

 

[daizeUK]

The flow rate is of interest to planted aquariums where a 10x turnover is advised to distribute CO2 and ferts (that's 10x with media loaded, obviously).
Personally I've got an Eheim Classic and I'm pretty sure they're one of the few externals rated for flow with media loaded so I'd be interested to test if that's correct.

 

[KirkyArcher]

I thought this would be good and would have liked to get involved but realised that having in-line UV steriliser and Co2 diffuser would also corrupt results along with having non standard media arrangement in my Fluval 206/306's

 

[KirkyArcher]

The flow rate is of interest to planted aquariums where a 10x turnover is advised to distribute CO2 and ferts (that's 10x with media loaded, obviously).

 
Just based on the EFX 400 filter quoted to get your desired 10x turnover using that model and even without media it's rated for 400 litre tank but is only suitable for a 140 litre tank and with media will only suitable for a 45 litre tank.  Bit of an eye-opener as to how "under filtered" you can be but think your choosing correctly based on packaging claims

 

[daizeUK]

That's why many of the planted folks use a powerhead in addition to the filter  but it's useful to have the figures so you know which filters are giving you the best flow rates on their own too. 

 

[IndySE]

My Fluval G3 shows the flow rate on the screen as 'EC us/cm = 754".
 
Once I've worked out what that means I'll edit the post lol! 
 
Cheers,
Indy

 

[Metka]

IMO there is not good way to compare flow rates except w/o any media. Otherwise one must use standard media loads and test them 1005 clean. After that you change results to much to be useful. But then media volume is more important than flow rate when it comes to filtration and dwell time is important too.
 
Using too large a filter with the flow rate turned down is better than a smaller filer at a higher flow rate.

 
I understand where you're coming from, but figures based on flow rates without media are just 100% useless. That is why I've added the Contributing factors: bit, so people can add their own filter material specs. That way, overtime, we can gauge that "this filter with standard filter material is crud, but change the filter media for 'this' and it works 10% better!"...etc
 
Lets get some data going people!!

 

[Ch4rlie]

It's a good idea but there's a few issues.

TTA has pointed out some flaws already and getting accurate data may be compromised by some margin as there are many different types of non standard filter media, flow output control valves, how much crud and muck inside filters, age if filters also are variables that will need to be accounted as well.

However, it would be good to have say, mean averages of flow rates for filters as a guide, cannot be exact figures due to the variables already mentioned above.

Does this data collection include internal filters too?
There are hundreds of models out there so you'd need at least 3 data figures, minimum, from each particular model before you could calculate an average figure for flow rates.

Can you tell me how you'll get internal flow figures, not as simple as putting a bucket under the internal as most internals are in fact already in water and most cannot be run dry, fitting an appropriate sized hose on outlet pipe/hole and flow water into bucket. Would that work appropriately?

For me personally. It's gonna be a bit of a faff to get the figures you want. I have a TetraTec EX1200, outlet hose attached to spraybar etc etc. I could disconnect spraybar and attach another hose to outflow pipe and to bucket. But I don't have any leftover hose long enough to do this, so I'd have to buy another meter or two of hose basically just for this purpose. Once job done get everything back together again.

I can do this but not everyone is willing to go to too much trouble for this.

So any suggestions to help these folks to gather data for you would be appreciated.

Hope it works out as would make interesting reading