Do I need external filter for my low tech?

Sacha

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Hi all,

I've had my Juwel Rio 240 running as a successful low-tech since December. Lightly stocked with fish and shrimp - no trace of algae and plants growing slowly but steadily. Lots of floating plants.

I'm using the Juwel internal filter with an upgraded 1,000 lph powerhead, and in addition I have an Eheim Professionel 3 600 external filter.

The Eheim broke a week ago - just stopped working. I ordered a replacement but it still hasn't arrived. In the meantime I have added a Koralia Nano powerhead for additional flow.

Now, the fish seem happy as ever, the tank is spotless and I have noticed no ill effects of losing the external filter.

Do I actually need to replace it or shall I cancel the order?

Thanks in advance.

Sacha
 

kilnakorr

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Now, the fish seem happy as ever, the tank is spotless and I have noticed no ill effects of losing the external filter.
You seem to have answered your own question;)

If your flow is good and the internal filter can keep the tank clean plus keep enough good bacteria then no need for another filter.
You probably lost a lot of bacteria when the filter broke, so pay attention to the tank, and maybe up the waterchanges until the beneficial bacteria in the internal filter has populated.
All depends on how stocked your tank is:)
 

dw1305

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Hi all,
Now, the fish seem happy as ever, the tank is spotless and I have noticed no ill effects of losing the external filter.
You seem to have answered your own question
That would be my thought as well. The <"plants are grown in">, you have plants with Diana Walstad's <"aerial advantage"> and you still have <"stable and resilient biological filtration">. My guess would be that you also have a similar size of gas exchange surface using the Koralia.

It is really up to you whether you replace the external filter. It will give you <"extra biological filtration capacity">, but you have two sources of water movement as is.

cheers Darrel
 

Tim Harrison

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I'd cancel the order. Juwel internal filters are pretty well designed and will do the job on their own very well low-energy and especially in a planted tank. The only downside is the lack of flow, but you seem to have addressed that too.

I ran a low-energy tank with just the Juwel internal filter for years. To solve the flow problem I hooked up a pipe directly to the outflow of the powerhead with bits and pieces so it came up over the weir giving me directional flow. Image below should give you some idea. It'd be easy to come up with something a bit more sophisticated these days probably just with Eheim parts.
 

Attachments

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Just a thought but if the biological load has been split equally between internal and external then you may have lost 50% of your biological filtration? This isn’t to say the internal may eventually be able to cope though. Just wondering what may happen in the meantime?
 

dw1305

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Hi all,
Just a thought but if the biological load has been split equally between internal and external then you may have lost 50% of your biological filtration?
I understand were you are coming from, but you don't need to worry too much, mainly because the tank is a established planted tank.

The 50% loss scenario would only be the case if you had a tank without any plants or substrate, where you were entirely reliant on microbial biofiltration within the filter.

Even then (in the "bare tank" scenario) it would be dependent upon the amount of dissolved oxygen reaching the filter media. Often external filters run at a fraction of their nitrification potential because the water becomes deoxygenated within the filter. As long as removing one filter didn't reduce the amount of oxygen in the water you won't have changed the biological filtration potential, because it's nearly always dependent on the amount of dissolved oxygen in the water, not the volume of filter material.

Once you've added growing plants and a substrate you have created a much larger area where nitrification can occur, both in the upper layers of the substrate and in the <"rhizosphere surrounding the plant roots">. You also have to factor in the amount of fixed nitrogen removed directly by the plants, and their net oxygen production.

<"Plant/microbe" biofiltration"> can potentially deal with bioloads (Biochemical Oxygen Demands (BOD)) an order of magnitude larger than "microbe only" systems. There are no "plant only" systems, because plants will always have associated microbes.

cheers Darrel
 

Sacha

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Thanks for all the quick replies - that's all really helpful. I think it's clear that the external filter is unnecessary as long as I provide sufficient flow and distribution throughout the tank. I agree that the Juwel internal is more than capable of providing sufficient biological filtration (in combination with the plants of course).

My main concern is therefore regarding flow and circulation. Please see below video which should give a decent idea of the distribution in the tank. As you can see, I have the internal filter outlet pointing horizontally across the tank and angled slightly diagonally. The Koralia powerhead is also pointed horizontally across the tank and is positioned about halfway down the depth of the water.

There appears to be good flow on the right-hand side of the tank, but possible dead spots on the far left (where the Amazon swords are). From the video below, does anyone have any suggestions as to how I could improve the distribution of flow using the internal filter plus powerhead?

 

dw1305

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Hi all,
From the video below, does anyone have any suggestions as to how I could improve the distribution of flow using the internal filter plus powerhead?
Not really anything about the flow, but I might thin out the floating plants to give you about 50% open surface.

cheers Darrel
 

Sacha

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Cheers! I already thinned out around 50% over the weekend - you should have seen it before! Don't suppose anyone wants a big bag of duckweed.......
 

kilnakorr

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From the video below, does anyone have any suggestions as to how I could improve the distribution of flow using the internal filter plus powerhead?
Put the powerhead higher and aim at the front glass in an angle. Should easily be able to reach the other end.
 

alto

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When I had Juwel Aquariums, I just ran them with stock lighting (sometimes upgrading to the dual light option) and filters - mine were much more densely planted with no additional flow ;)
 
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