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Most L numbers like a bit of water movement. In fact most like more flow than we can reasonably generate in our tank. (If you don't have the means like Pantarhei in Germany that is! https://www.youtube.com/watch?v=UKpWqgbkwSA)

I can't figure out what I should do with my water flow at night. I keep the filter running at all times.

At the moment however, I turn the powerhead off mainly because I want the fish to have a calmer night cycle, and to minimize the noise from the tank.

I know the reef community have to run them 24/7 because of the corals, and the lesser oxygen at night. Is it as important for our freshwater plecos?

What do you guys do?

Mine run 24/7 in my 120 gallon with my plecos and cories. Rivers don't stop running at night so the powerheads don't either ;)

You have a valid point

They do love the new flow in the tank, thats for sure. I have added a Maxpect Gyre XF250, developed for reef tanks, but its sublime in its recreation of a river flow too, everything is in motion!

I might just leave it on.

at night riers don´t stop running indeed. But further, plants, including algae, produce oxygen during the day, and carbon dioxid during the night. Therefore, if you would stop the powerhead for 12 hours, do is during the daylight

But mucht better, don´t. Ever.

Hi all,

Bas Pels wrote: ↑06 Aug 2017, 19:55 at night rivers don´t stop running indeed. But further, plants, including algae, produce oxygen during the day, and carbon dioxide during the night. Therefore, if you would stop the powerhead for 12 hours, do is during the daylight

But much better, don´t. Ever.

I agree with @Bas Pels. I definitely wouldn't turn them off.

If you have un-planted tanks there isn't any difference between night and day, but while planted tanks tend to have higher oxygen levels than un-planted tanks (there are a number of reasons for this (http://plecoplanet.com/?page_id=829)) the plants will contribute to the bioload at night, when they aren't photosynthesising.

cheers Darrel

Thanks.

That's a great article. It further underlines why constant aeration is important, especially for rheophilic species like many L numbers.

Ill leave them on!

Hi all,

Cydone wrote: ↑07 Aug 2017, 15:00 That's a great article. It further underlines why constant aeration is important, especially for rheophilic species like many L numbers.

Thank-you, I wrote it about ten years ago, and it has had a few different homes, but I still refer to it because it is still relevant.

I will update the references at some point.

cheers Darrel

I think my next logical question would be, should I use a constant flow pattern, so as to mimic how the river (upper orinoco) flows, or could I change the flow rate during the day?

Rivers change flow rates after heavy rainfall, but they probably don't change much during normal days.

Right now I'm using a 5300 gph maxpect gyre pump on my 225g tank. I have set it to go from 10%-20%-30% and down again during the course of the day. (My plecs love every % this pump can give, and would probably prefer 100%, which is an insane amount of circulation)

Would a constant flow be more natural?

Fluctuations in flow (not daily, but maybe over weeks) may trigger a species to spawn, but I would think otherwise serves little value. I'd think that it's more important to have some spots in the tank where flow is disrupted and slowed all the time (but not dead still... That too can be bad). Fish which don't like flow can stay in these quieter areas, and fish that like flow can also come here to relax or whatever they want to do, just for an alternate activity choice.

Not sure that's right, but it seems logical to me.

Cheers, Eric

bekateen wrote: ↑16 Aug 2017, 14:45 Fluctuations in flow (not daily, but maybe over weeks) may trigger a species to spawn, but I would think otherwise serves little value.

I can imagine this would work, for instance for fish from the Himalaya. Or other mountains in Asia. There the musson is very important - the period with all the rain a year brings. And little water implies little current.

But most often the dry season furhter brings heat, little food and bad water. Personally, I think these might be more important triggers for spawning than the current.

Still, if an ordinary dry season (water + 3 degrees, half the food and no or much less waterchanges for a month) does not work, one might go further and prvide less current.

But in such a case the risks of loosing fish becomes increasingly higher

Bas Pels wrote: ↑17 Aug 2017, 07:46But most often the dry season furhter brings heat, little food and bad water. Personally, I think these might be more important triggers for spawning than the current.

Yes I agree. It may not be the current per se that triggers spawning, but what the current carries (refreshed water, lower temperatures, oxygen, foods). From a mechanical perspective, current can change the riverbed, either bringing or carrying away sediment and debris. This could theoretically provide spawning sites. Scientifically, it will be a challenge to tease these factors apart and weigh their priority.

Thanks, Bas Pels, for that comment.

Cheers, Eric

Interesting points.

I have been very inspired by this post on rainy/dry season in our aquariums. http://www.plecoplanet.com/forum/showthread.php?t=650

I'm trying to make it so I do my water changes on rainy days with low pressure, and then increase the flow. Colder water and more flow plus low pressure, should mimic heavy rainfall. Also when there is a low pressure, I will increase flow. This ill have to do manually of course.. imagine a pump that took air pressure into account, and lowered/increased flow accordingly.

My idea with the post, in essence, was really how can I recreate a flow environment as close to my fish' natural habitat.