Does good 'flow and distribution' always require high current?

[Andy Pierce]

I 100% agree that fish look more relaxed in the absence of flow. It would be great to have the best of both fauna and flora worlds.

I did a little mini experiment last light looking at the effects of flow on fish behaviour. Link to video: Fish behaviour: water flow vs. lighting, Fireplace aquarium. I too thought flow was having a big influence on fish behaviour but now I'm much less convinced - my fish at least seem completely unperturbed by greatly increased water flow. What DOES have a huge influence though is lighting. The effect of the flow is subtle but light influences are immediate and dramatic. I noticed different behaviour in the process of transitioning from a low tech to high tech setup which at the time I attributed to installation of a powerhead, but now I'm thinking it was actually the significantly upgraded lighting that was the main driver.

 

[Paul Kettless]

I did a little mini experiment last light looking at the effects of flow on fish behaviour. Link to video: Fish behaviour: water flow vs. lighting, Fireplace aquarium. I too thought flow was having a big influence on fish behaviour but now I'm much less convinced - my fish at least seem completely unperturbed by greatly increased water flow. What DOES have a huge influence though is lighting. The effect of the flow is subtle but light influences are immediate and dramatic. I noticed different behaviour in the process of transitioning from a low tech to high tech setup which at the time I attributed to installation of a powerhead, but now I'm thinking it was actually the significantly upgraded lighting that was the main driver.

No question, I just watched all of the video, and the nothing to everything startled the fish, a gradual increase in light is the ideal way. as this video only showed a minute of activity after the light is on to do you notice with time that the fish come from under the plants and swim more openly?

 

[Hufsa]

but light influences are immediate and dramatic.

What an interesting video 😮 I agree that really was a dramatic change, the light does look super bright but that may be influenced by the video capture I suppose. In respect to your specific situation I would wonder if its possible to reduce your lighting a bit?

There may be some difference in requirements from fish to fish, well it seems obvious when I put it this way but a "tetra" is not a "tetra" in all cases. Or what I mean is schooling fish may have very different requirements. Both me and @Wookii have Boraras, which come from fairly still blackwaters. At least all videos ive seen of Boraras sp. in nature has been in little pools with minimal water movement. Not completely stagnant but minimal water movement. So its possible that I should aim for a lower water velocity than you might get away with having your active Rummynoses.

Its hard to write this without sounding rude, but in regards to the contibution by @reefkeeper1 , I would much rather be accused of caring too much than caring too little. Do I have a tendency to overthink? Definitely, but I think its worth it. I wish you could find a better way to phrase some things, as the good points you make get lost in the somewhat abrasive way you present it 🙂

This thread may be morphing into a "how to increase our fishes' comfort level", but I think thats great. I get the impression sometimes that fish are added almost as an afterthought to aquascapes, and that seems like a shame to me. Their needs should come first and plants should come second. But I think with some experimenting it should be possible to have comfortable fish while still facilitating good plant growth. Good plant growth is good for the stability of the tank and therefore the fish, after all.

 

[Andy Pierce]

No question, I just watched all of the video, and the nothing to everything startled the fish, a gradual increase in light is the ideal way. as this video only showed a minute of activity after the light is on to do you notice with time that the fish come from under the plants and swim more openly?

Time after the lights come on, even hours later, doesn't really seem to change their behaviour; as long as the light is on they stay towards the bottom. There are photos rather than video here: Lights on – lights off!, Fireplace aquarium where in the "lights on" photo the light has been on for over 5 hours already. The fish aren't right down under the plants but they are down in that bottom right quandrant and the photo is reasonably representative of their general lights-on behaviour. The "lights off" photo is 50 minutes after the lights have been turned off, which doesn't look obviously different to the video where the lights have been off for hours. It would be interesting to see whether a gradual increase/decrease in light levels makes a difference, but my set-up isn't equipped to do that. If someone else wants to put something together I'd be really interested in seeing it.

That being said, I was mainly trying to determine whether flow was changing the fish's behaviour and I'm pretty confident now that it is not, at least not with these fish (rummy nosed tetras, 5-banded barbs and otocinclus catfish) in my setup.

 

[Emil.]

I was mainly trying to determine whether flow was changing the fish's behaviour and I'm pretty confident now that it is not

Excellent video, thanks Andy! I don't think light and flow are mutually exclusive in hiding the fish, however. Imho, they hide from light to be safe and they hide from high flow to rest their fins. It's definitely good to know that light plays a factor too.

 

[Emil.]

Im amazed that more aquascapers dont use wavemakers/powerheads more in there aquariums. After all "wavemaker" sales pitch is just a pump that is fully controllable in speed

Paul, that's brilliant. Provided that wavemaker can distribute ferts & co2 adequately every day, I like the idea of having just sponge filter as a filtration. Super easy maintenance, plenty of oxygen all the time and large rest intervals for the fish when the wavemaker is off. The only downside is that the diffuser and heater would need to go back in the tank but I bet it can all be hidden. Has anyone tried this setup?

 

[Paul Kettless]

Paul, that's brilliant. Provided that wavemaker can distribute ferts & co2 adequately every day, I like the idea of having just sponge filter as a filtration. Super easy maintenance, plenty of oxygen all the time and large rest intervals for the fish when the wavemaker is off. The only downside is that the diffuser and heater would need to go back in the tank but I bet it can all be hidden. Has anyone tried this setup?

I cant see no reason why it wouldnt all wavemakers are designed for is to assimulate current and help you eliminate dead spots. going back to a reef tank again, the pumps would be working harder at the times when the dosing machine was working to try and evenly distribute around the tank. When lights out the pumps would slow considerably, no different to how you would work lights, co2 and ferts i guess.

 

[Andy Pierce]

I did a little mini experiment last light looking at the effects of flow on fish behaviour. Link to video: Fish behaviour: water flow vs. lighting, Fireplace aquarium.

I followed up with a video of what happens when the light turns off at the end of the day: Fish behaviour: water flow vs. lighting – pt 2, Fireplace aquarium. It is largely the reverse of what happens when the lights turn on except slightly more gradual where the fish that swim at the bottom come back up above the midground plants when the light goes off. Same story with the two different powerhead speeds as before with very little effect on how the fish behave. I'm pretty convinced it is the actual state of the light rather than the abruptness of the transition that matters. Anyone else see an obvious effect of lighting on fish behaviour? It may be simply that in a larger tank there's less of an effect.

 

[john dory]

Yes,certainly.
Watching my fish,as we speak(lights off)..in well over 10 times(stated)flow.
Probably nearer 20x
Just milling around in the tops of the stems.

 

[john dory]

Regarding flow patterns

Sent across the front length of the tank,by the time it's bounced off the far end..forced down..and then back across the rear.
There's only enough to gently rock my stems.

That's a 600 biomaster coupled with a powerhead of similar output,in a 1 metre long tank,containing 150l of water.

 

[Sammy Islam]

I followed up with a video of what happens when the light turns off at the end of the day: Fish behaviour: water flow vs. lighting – pt 2, Fireplace aquarium. It is largely the reverse of what happens when the lights turn on except slightly more gradual where the fish that swim at the bottom come back up above the midground plants when the light goes off. Same story with the two different powerhead speeds as before with very little effect on how the fish behave. I'm pretty convinced it is the actual state of the light rather than the abruptness of the transition that matters. Anyone else see an obvious effect of lighting on fish behaviour? It may be simply that in a larger tank there's less of an effect.

I have noticed that my ember tetras become "playful" and "adventurous" when my lights start ramping down. During lights on they are pretty stationary chilling in the bottom 3rd of the tank. After lights out they "sleep" in the top 3rd of the tank.

 

[jaypeecee]

I’ve even considered whether it would be possible to have pipe work under the substrate feeding sprinkler type head at various points (hidden from view by hardscape of course) allowing slow outflow across the bottom of the tank...

Hi @Wookii

I remember having had that very discussion with you what must have been a couple of years ago.

JPC

 

[Wookii]

Hi @Wookii

I remember having had that very discussion with you what must have been a couple of years ago.

JPC

Well that line you've just quoted is from 2 years ago John 😂

 

[hwscot]

Late to this. My dream setup is a long stream-like tank, relatively wide and shallow. I came across the thread just the other day. I've been playing around with the idea of using a water blade to deliver flow into the tank, which from reading this thread, would be my alternative to a spray bar set up with large holes.
Part of my thinking comes from having had a large garden pond (before vandals made it non-viable, sadly) with the traditional top pond and a waterfall.
Instinctively the blade seems to me more natural in appearance than a spray bar, and a more uniform width of flow (the width of the stream, in effect) likely to give more of the effect of a large volume of water moving steadily down the length of the tank.
A weir as the outflow from the tank would be the natural other end of the stream. And I guess, in effect, the blade is not so different, in terms of flow 'shape', from a weir, but potentially simpler to manage if it simply connects to the pipework from the filter or pump. Blades come with either a rear or base input to the box.
Apparently a blade needs c. 1000 lph per ten cm width of blade to get a decent flow, so a blade say 20 or 30 cm wide on a tank of, say, 300 litres, doesn't sound so unreasonable. Lots of issues with the 'plunge pool' effect on substrate etc. but my notion was to have the lip of the blade only, say, 10cm above the water surface. Noise migh be an issue for some people, although possibly not much more than a large HOB. And I like the noise anyway. (the waterfall helped mask noise from a nearby road, and I find it relaxing).
Has anyone seen this tried? I'm guessing there must be tanks with a weir as input at one end and another as output at the other end; they would be interesting to look at while mulling all this over.

 

[jaypeecee]

Has anyone seen this tried? I'm guessing there must be tanks with a weir as input at one end and another as output at the other end; they would be interesting to look at while mulling all this over.

Hi @hwscot

I suggest that you take a look at so-called 'river tanks'. This is a suggested layout:

The secret to setting up a better river aquarium

www.practicalfishkeeping.co.uk

One possible candidate fish for such a setup is one of my favourite fish - the Hillstream Loach - an example of which you'll find here:

Hillstream Loach - Habitat, Care, Feeding, Tank Size, Breeding - AquariumNexus

Fish and other water creatures survive in a range of environmental conditions provided they are habitable. Being a hobby aquarist means that the animals you choose for your tank will be easy to keep and will thrive, provided you have the right tank conditions for them. One of the common options...

www.aquariumnexus.com

And, here's some reading material:

Gastromyzon punctulatus summary page

www.fishbase.de

Sewellia lineolata – Tiger Hillstream Loach (Balitora lineolata, Sewellia songboensis) — Seriously Fish

www.seriouslyfish.com

Note the flow rate of water in the natural habitat for hillstream loach, i.e, > 1 meter per second!!

Just thought this might be of general interest.

JPC

 

[Garuf]

It’s my understanding a lot of the bigger plecs are from insanely high water speeds too.

 

[Wookii]

Late to this. My dream setup is a long stream-like tank, relatively wide and shallow. I came across the thread just the other day. I've been playing around with the idea of using a water blade to deliver flow into the tank, which from reading this thread, would be my alternative to a spray bar set up with large holes.
Part of my thinking comes from having had a large garden pond (before vandals made it non-viable, sadly) with the traditional top pond and a waterfall.
Instinctively the blade seems to me more natural in appearance than a spray bar, and a more uniform width of flow (the width of the stream, in effect) likely to give more of the effect of a large volume of water moving steadily down the length of the tank.
A weir as the outflow from the tank would be the natural other end of the stream. And I guess, in effect, the blade is not so different, in terms of flow 'shape', from a weir, but potentially simpler to manage if it simply connects to the pipework from the filter or pump. Blades come with either a rear or base input to the box.
Apparently a blade needs c. 1000 lph per ten cm width of blade to get a decent flow, so a blade say 20 or 30 cm wide on a tank of, say, 300 litres, doesn't sound so unreasonable. Lots of issues with the 'plunge pool' effect on substrate etc. but my notion was to have the lip of the blade only, say, 10cm above the water surface. Noise migh be an issue for some people, although possibly not much more than a large HOB. And I like the noise anyway. (the waterfall helped mask noise from a nearby road, and I find it relaxing).
Has anyone seen this tried? I'm guessing there must be tanks with a weir as input at one end and another as output at the other end; they would be interesting to look at while mulling all this over.

There are quite a lot of River/Stream tanks out there of different designs. The one in my post #60 in this thread is one of the best, and cleanest designs I've seen (20,000 lph):

(Time stamp 06:25 onwards)



In this video with Jurijs Jutjajevs, you can see a lot more of the technical construction etc:



Same tank design (could even be the exact same tank) shown here, and looks really nice:



There is also this tank (referenced in the above video also), that actually uses a sloping tank to help achieve the high flow:



More details also at the start of Georges video here:

 

[Conort2]

It’s my understanding a lot of the bigger plecs are from insanely high water speeds too.

Most l numbers love high flow, even the smaller hypancistrus, peckoltia etc thrive with it. Corydoras too, many species spawn directly in the flow of power heads.

There are quite a lot of River/Stream tanks out there of different designs. The one in my post #60 in this thread is one of the best, and cleanest designs I've seen (20,000 lph):

(Time stamp 06:25 onwards)



In this video with Jurijs Jutjajevs, you can see a lot more of the technical construction etc:



Same tank design (could even be the exact same tank) shown here, and looks really nice:



There is also this tank (referenced in the above video also), that actually uses a sloping tank to help achieve the high flow:



More details also at the start of Georges video here:

Love the panta rhei tanks, definitely a if I win the lottery type set up though!

 

[hwscot]

There are quite a lot of River/Stream tanks out there of different designs. The one in my post #60 in this thread is one of the best, and cleanest designs I've seen (20,000 lph):

Saw that in the earlier post .. it's stunning. Really useful to have a bit more information about how it works.

 

[Wookii]

Saw that in the earlier post .. it's stunning. Really useful to have a bit more information about how it works.

It’s an amazingly simple design when you see it - and I can’t believe they get all that flow with just a single Gyre style flow pump. 20,000 LPH isn’t even the biggest of those style of pumps - as @Conort2 says, if I won the lottery there’d be a nice 3 or 4 metre river tank like that in the new millionaires pad!