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  1. #1

    advise for new filtration on a pump fed, retrofit bottom drain

    got an approx 4000 gallon in ground "natural" pond with a stream.

    at the moment just have 2x in pond pumps 1 to the stream and 1 to a multibay (this is what looking to replace).

    I also have a vario dry mounted pump and 2x dry mounted, so am looking to also change to dry mounted.
    I do have a cetus sieve lying around

    unfortunately haven't been able to persuade to go in ground bottom drain, so it's a pump fed to multibay above water level (and can't get it a filter to be water level unfortunately).

    we will be building a top pond for the stream where i was hoping to put in filtration plants/anoxic baskets

    a shower isn't a possibility

    space for filter isn't really an issue, we can either locate it about 6ft away from the pond or 20ft.

    the big question is what's recommended to replace the multibay and with easier cleaning?

    can a drum filter be fitted above water level?

    i'm pretty sure they won't go for trickle in and out system either, so not 100% even if a drum was an option for above pond level even if i could fit one.

    is a nexus 320 the best option for us?


    in reality whats the actual difference between doing a large 3 bay with vortex clean once a week compared to a trickle in/out on a drum?


    Last edited by CBKOI; 14-05-2021 at 02:07 AM.

  2. #2
    Quote Originally Posted by CBKOI View Post
    got an approx 4000 gallon in ground "natural" pond with a stream.

    at the moment just have 2x in pond pumps 1 to the stream and 1 to a multibay (this is what looking to replace).

    I also have a vario dry mounted pump and 2x dry mounted, so am looking to also change to dry mounted.
    I do have a cetus sieve lying around

    unfortunately haven't been able to persuade to go in ground bottom drain, so it's a pump fed to multibay above water level (and can't get it a filter to be water level unfortunately).

    we will be building a top pond for the stream where i was hoping to put in filtration plants/anoxic baskets

    a shower isn't a possibility

    space for filter isn't really an issue, we can either locate it about 6ft away from the pond or 20ft.

    the big question is what's recommended to replace the multibay and with easier cleaning?

    can a drum filter be fitted above water level?

    i'm pretty sure they won't go for trickle in and out system either, so not 100% even if a drum was an option for above pond level even if i could fit one.

    is a nexus 320 the best option for us?


    in reality whats the actual difference between doing a large 3 bay with vortex clean once a week compared to a trickle in/out on a drum?
    If you buy a pump fed drum it can be above pond level with gravity return. Your biological filter would also need to be above ground with the water flowing from your drum straight into the bio section / unit.

    You can buy a combi drum (which includes the drum and a bio section in one unit) or separate drum and bio filter tank(s).

    If you went for a “standalone” pump fed drum or combi I think it would be very difficult to install a Nexus afterwards (how would you get water from drum into Nexus - imo a risky costly plumbing nightmare). Obviously you will have the same problem if you try and install the pump fed sieve in front of the Nexus.

    You can buy a Draco drop in drum for the nexus but I don't know if these can be pump fed. Also, I think flow rate is limited.

    I’m sure other forum members will correct me as needed!

    There are many drum manufacturers but I run Oase proficlear drums and think they’re very good. Depending on your stocking level etc it sounds like the Proficlear Compact L combi (not the smaller medium “M”) is better suited for your pond size but it will depend on how large a bio filter you need. If you have lots of fish it might be better to buy a separate drum and biological filter unit(s) (increased media capacity).

    https://www.oase.com/en/products-a-z...d-egc-int.html

    I used to have Nexuses and unless you already own one I wouldn’t bother buying one - mechanically they let alot of large fines through (400 microns+) unless you use the Draco drop in drum. Biologically they are excellent but imo its probably easier, more practical and cheaper to buy a drum system, either combi or individual units connected together.

    Good luck with your refurb!

  3. Thanks CBKOI Thanked / Liked this Post
  4. #3
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    You could keep the multi bay, using all its chambers for bio media, and add a pump fed drum in front of it. You would need the drum to sit higher than the multi bay to do this.
    There is really no advantage to a Nexus over a multibay other than ease of cleaning, but a drum followed by anything at all biological is much less maintenance and performs better.

    Having a drum doesn’t mean you need to trickle in. However your drum will need a mains connection for its spray bar feed, and a waste outlet to a drain or a large soak away (not suitable in all gardens).

    If you wanted to use a dry mounted pump on a retro bottom drain then the pump itself would either have to be below pond water level, or a special self priming pump. None of the usual pond pumps are self priming.

  5. Thanks WaterRhino Thanked / Liked this Post
  6. #4
    ah thanks for that, recommendation for pump fed drum?

    and good to know about not needing trickle in and out, so mains and waste is no issue either.

    Sent from my kukui using Tapatalk

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  8. #5
    Quote Originally Posted by CBKOI View Post
    ah thanks for that, recommendation for pump fed drum?

    and good to know about not needing trickle in and out, so mains and waste is no issue either.

    Sent from my kukui using Tapatalk
    Feline’s is a good idea, if you have the space and can raise the drum to feed the multibay it could be very cost effective.

    If you retained the multibay you’d likely need to change your filter media over in the multibay gradually to avoid a massive collapse in biological capability and a corresponding dangerous rise in ammonia (and nitrite).

    alternatively you could leave the multi bay working with its existing bio and at the same time fishless cycle the new media . Once the fishless cycle was complete (8-12 weeks typically) you could then start swapping out the old media for the new (probably again gradually to ensure there were no unforeseen problems).

    i had to use this approach a few years ago when my fish outgrew my biological filters and had persistent high levels of ammonia. I couldn’t add another filter and had to upgrade my HelX to pond pads. It took 12+ long weeks to fishless cycle the pads (a bay at a time) but the swap over plan worked, aided by water changes of course.

  9. #6
    thanks for the advice, decided on the Nexus 320 with auto cleaning that's for sale on here.

    i think that'll be the "safest" option for the parents and less hassle on setting up for them now to be honest.

    no doubt i'll be back asking questions on setting up, etc....

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