does flow rate effect bacterial levels in internal filter?

Discussion in 'Filters, Filtration and Pumps' started by a1Matt, 2 Apr 2008.

  1. a1Matt

    a1Matt Member

    Messages:
    2,521
    Location:
    Bromley
    Hi,

    I understand that a higher flow rate in a tank is beneficial as it keeps the dirt suspended for longer and therefore gives the filter more opportunty to pick it up.

    Does the flow also have any effect on bacterial levels, or is that largely determined by filter material and size of filter? (I know that it will also depend on the condition/maturity of the filter)

    As always thanks for any replies posted :D

    (The reason for my question is that I have a fluval 4+ internal power filter, with standard foam media. [the tank is 160L, currently with 75W lighting by the way]. The fluval is currently turned to its lowest flow rate and I wonder if cranking it up will help and in what ways.)
     
  2. Ed Seeley

    Ed Seeley Member

    Messages:
    3,262
    Location:
    Nottingham
    Personally I'd up the flow rate. The extra flow will help for getting dirt to the filter more quickly and also in supplying nutrients and CO2 to all the plants. The bacterial growth is very dependant on the bioload of the tank more than flow rate, as long as you have sufficient surface area in the filter media.

    However foam on its own, IMO, is not the best media for bacterial growth. I think you could really do with a larger media area that allows a range of filter media.
     
  3. Steve Smith

    Steve Smith Member

    Messages:
    4,428
    Location:
    Leamington Spa, UK.
    You can get a spray bar attachment for the FLuval 2+ 3+ and 4+ filters if that helps. Might give a better flow without being too strong.
     
  4. a1Matt

    a1Matt Member

    Messages:
    2,521
    Location:
    Bromley
    Great advice guys, thanks. 8)

    I will up the flow rate.

    I think I have a spray bar attachment knocking around somewhere, so I will try with and without that. ;)

    Although my tank size hasn't changed over the last year the bioload has significantly increased (3 times as many fish, 3 times as much lighting, Co2, EI, 10 times more plants!). So I think it is time to start seriously looking into getting a larger filter that can take more media.

    Thanks again.
     
  5. ceg4048

    ceg4048 Expert/Global Moderator Staff Member

    Messages:
    8,952
    Location:
    Chicago, USA
    I agree with Ed in that you should consider replacing the foam with biomedia that has a higher surface area. In that way you can cultivate a higher bacterial load. Flow rate within the filter does affect it's performance in that higher flow delivers more ammonia laden water to the colony. A lot of this advantage is lost however if the surface are of your media is saturated with bacteria. The growth of the colony is arrested since there is no place else for additional bacteria to attach. Flow rate also is important in that outside the filter because the nutrients and CO2 in the water column can be delivered efficiently to the surface of the leaves. You should never reduce the flow in a high light tank. The bacteria colony is your ally because they remove ammonia which is the source of algal growth. Ideally therefore you would have an external canister filled with high surface area sintered glass media and a high throughput. The next best thing is to slowly replace the foam in your existing internal filter with high surface area media and to turn the flow rate to MAX.

    Cheers,
     
  6. a1Matt

    a1Matt Member

    Messages:
    2,521
    Location:
    Bromley
    That is a great explanation, nicely deconstructed. I think I have a good understanding of it now.

    I had been dallying with the idea of a new external canister filter for the last week or so anyway, the replies to this post have made it a definite ;) Having said that I will not rush out and buy one straight away as I want to spend some time researching the different filters available, and the different media available for them. All weighed up against the cost as well!

    I think my current filter will hold up fine in the short term. I just won't push the tanks bioload any further :rolleyes:
     
  7. a1Matt

    a1Matt Member

    Messages:
    2,521
    Location:
    Bromley
    I thought I'd feedback with an update...

    4/5 days ago I turned up the flow rate from minimum to near maximum.
    You can see a noticeable increase in the current.

    There is one area of the tank that is now a no go zone for all the fish :wideyed: except the guppies and flying foxes as the current is too strong. I can live with that as the guppies absolutley love playing in it :D and the other fish have plenty of space still.

    I always had some dirt on the gravel, I just expected this when keeping a tank... now I have pretty much none :p

    Its too early to tell the effect on the plants, but I see better movement of the current through the leaves, so expect it will have improved CO2 circualation, which can only be a good thing :D
     
  8. a1Matt

    a1Matt Member

    Messages:
    2,521
    Location:
    Bromley
    Another update...

    Over a few weeks the improved flow resulted in better growth on the lower leaves of my stem plants, which from Clives posts I take to be from the improved Co2 and nutrient distribution created by the higher flow rate.

    I also have a noticeably cleaner aquarium and the filter clogs up sooner than before.

    So this weekend I went out and purchased a Tetratec EX1200 (and a Hydor ext heater). It's a bit noisy but an otherwise excellent upgrade from the Fluval 4+. It came with media included, which I will probably look to change in the future in some way (am thinking of sintered glass).
     

Share This Page

Facebook Page
Twitter Page
  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.
    Dismiss Notice