Experiment – How much does changing microfilters really affect broadband speed?

Often times when we have a connection issue with our internet, the ISP support team amongst other things tell us to swap microfilters or get replacement ones but how much difference do they really make? Let’s find out.




So the structure of this article will be as follows, my reason for doing such an experiment, the methods involved, the results and my overall conclusion. Let’s begin!

My reason for doing this experiment



Okay so I was tidying up my room and I came across some old BT MicroFilters, in total I had 6 (including the one that was actually being used with my router), i.e. 5 were spare, all I had to do really was just bin two at random but I thought I’d make things interesting and see if there’s actually a difference between them, like are my download and upload speeds really affected just by changing the microfilters?

The Method

Firstly, I arranged all 6 microfilters next to each other on the table and I labelled them in a notepad as 0,1,2,3,4,5  as seen in the image above. This was so that I could compare them and know which microfilter gave which speeds because they’re identical in look and feel. I took the one to the farthest left (0) and connected that to my router and waited for the power, broadband and wireless lights to go steady blue. I then cleared all my browsing data with Chrome so as not to have any of http://speedtest.net/ (the website I used for the speed testing) cached. Then I restarted my laptop and BT Home 3 Wireless Router, waited a couple of minutes for both to stabilize.



Repetition Steps

Then I went on http://speedtest.net/ did the test twice, one after the other noting down the upload and download speeds in the table I made (seen below)

Blank Table

Blank Table

After the data had been recorded, I took out the MicroFilter that was connected to the router, took out the cables connecting to it and waited for the broadband light to go off. (See below)

BT Home Hub

BT Home Hub

Then I placed the filter I had taken out (in this case filter o) back in the arrangement with the others, then took the next filter to the right (filter 1) carefully so as not to mess up the arrangement; it was imperative that the order remained so that I didn’t get confused which speeds correspond to which filters. I then connected filter 1 back to the router and plugged the cables back into it and waited for the broadband light to become steady blue once again. Then I waited one minute for the connection to stabilize.

BT Home Hub

BT Home Hub

After this it was pretty much a rinse and repeat process of the “Repetition steps” outlined above. So with that being said, let’s move on to the results portion of this article.





The download and upload speeds are in Mbps and rounded to 2.d.p because that’s what Speedtest.net uses. Let’s re-order the table by the average download, highest to smallest:


Results Arranged

Results Arranged

The majority of consumers would agree in saying download speed is more important to them then upload speed hence why I arranged the table in this way.


Overall we can say that there’s not a huge difference between the microfilters because the range (between filters 3 and 5) for average download speed is 2.44 Mbps. However, for someone downloading a game or a huge file, it might shorten the download time by a few minutes. Similarly for upload speed, the range (between filters 0 and 2) is 0.09 Mbps, this is a really small difference and whether you’re uploading a file at 0.96 Mbps (filter 2) or 0.87 Mbps (filter 0) they would still take roughly the same time.

Based on the results table above, the three filters I kept overall were 3,2 and 4 with 3 being the one actively connected to my router after that experiment was done and 2 and 4 being the spares, I binned the others, no point having 5 spares right?

Ultimately, there’s not a huge difference in broadband speeds by changing microfilters but after a while microfilters can get faulty and this could cause intermittent drops in connection so a replacement would be necessary in that case.

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Thanks for reading, feel free to let me know your thoughts in the comments section down below.

Written by Purav, PDTechHD (My personal account is PDTalkinTech)



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I’m a 23 year old Maths Graduate, who has a great passion for technology and in my spare time I make videos on YouTube to show my passion. I'm also co-admin here at TeckComesFirst and I joined this site back in January 2012.
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  • Really cool article Purav! Very interesting and unique idea!

  • Cool article mate!!!!!!! Probably the most detailed i have ever seen :)!!! And a very interesting one!!!

  • NaijaMan

    Great article mate, never seen detailed material like this on microfilters, just the quick 2 minute explanation you get from ISP demo CDs lol. Looks like I’ll be needing to change mine since I have been experiencing connection drops recently.

  • Jack

    Great article matey.

  • really interesting findings here! I would not have expected it to make a difference!
    Would be interesting, although a bit boring to do I guess, to see a similar experiment keeping the Micro Filters in for a longer period of time, say 1 week, doing a number of tests at roughly the same time; i.e. test all filters at x o’clock on day 1 of their week, y o’clock on day 2 etc… Would give you a good feel to see if it was the filters or just time of day/local loading etc…

    (ps guess who has worked in testing/development for around 10 years :D)

  • Kumaran

    Cool article bro. More than i expected. My opinion is that, you should not have binned the spare one, should have just kept it, it might come handy one day. Cheers!! =D

  • Michael Fisher

    Thorough article. I know positively nothing about microfilters, but commend you on a rigorous and well-documented analysis. Well done!

  • Pretty interesting experiment!

  • Captain Reagan

    Hi there! I am a broadband techninition and I read through your article and I couldn’t help but notice you didn’t mention if the device you were using for the speed test was connected wirelessly.
    This can play a major role in how accurate these speedtests are for you. The best way to check your routers connection speed is to log into it’s status page by typing the IP address into a browser address bar