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Reduced Filter Flow At Night

simonm74

Member
Joined
3 Oct 2010
Messages
38
Hi folks,

I'm running an Eheim 2178 on a Juwel Vision 260 tank.

It has a 12-hour bio function which enables you to set two different flow rates, alternating every 12 hours.

I've set it up to to run at maximum flow during the day (to distribute nutrients and CO2) and minimum flow at night (to give the fish a rest and maximise the effectiveness of my UV sterilizer).

What are people's thoughts on whether this risks impairing its effectiveness as a biological filter, or de-oxygenating the tank at night when the plants are using up oxygen?

Pump ratings (according to the three baffling multilingual manuals which came with the filter) are:

Max pump output 1850lph
Max filter output (with media) 1100lph
Min filter output ("Min. filter capacity", whatever that is supposed to mean) 400lph
UV sterilizer max throughput for full effectiveness: 600lph
 

zozo

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16 Apr 2015
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I guess not realy an issue, if it was than a low flow, low tech tank, would be constantly in trouble. A low tech does not realy require the advised 10x turnover as with a high tech. In an average community low tech tank 4x to 5x is sufficient enough during the day as well as the night. I see no reason if there is no adding co2 during the night why the 10x turnover would be so important to keep intact since it is only an aim to get co2 evenly devided to al corners of the tank..

I ran my high tech for almost a year with barely 4 times turnover 24/7, couldn't realy say i had so much trouble with it on the filtering part only had some dead spots regarding co2, but the filter was not affected, at least didn't notice anything changing on that after increasing the flow. :)

I played with the same idea, since i use a dc 12 volt pump i can regulate with a dimmer, and thought of controlling it via the automated led controller and play with the flow speed during the day and night. I never did because i don't have a free channel on the controler for it at the time. But in a way i think it even could be beneficial for the fish to experience changes in flow speed. It would be more natural to them, since it occurs also in nature where they travel from lower to higher flow areas or when flow increases during rainy days. But that's just a theory i think about.. That flow isn't constant same speed in nature is obvious..
 

foxfish

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11 Oct 2009
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I can understand your concern, I can only speculate as to the effect on the biological bacteria but I could imagine that some bacteria would multiply during the main flow time and possibly die off during the reduced flow time?
I would guess that the filter would work more actively if it was left at full flow but the die off and re generation of new bacteria is obviously a natural process and I doubt if it would do any harm?
 

simonm74

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Thread starter
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3 Oct 2010
Messages
38
Thanks for your contributions. I've sacked this idea off for a number of reasons, the main one being that all the settings etc. get reset anyway when you turn the filter off at the mains (which I do most days to feed the fish!) I think I will just manually dial down the flow and turn the UV sterilizer on overnight once or twice a week.

I've come to the conclusion that pretty much all the expensive electronic functionality of this filter is useless gimmickry. It turns out that the flow is automatically reduced unless switch it out of "automatic" mode to "manual" (not, of course, that that is mentioned anywhere in any of the three accompanying manuals!)
 

ian_m

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25 Jan 2012
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Be careful with UV steriliser as it will unchelate you micro fertiliser rendering it unavailable for plants too use. Issues would be lack of iron.
 

simonm74

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3 Oct 2010
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Thanks Ian!

Yes I've heard that, but my thinking is that I should be OK as I do daily EI dosing.

My understanding of EI dosing is that every day we dump in more ferts than the plants can use in a day, which is why a big weekly water change is needed.

So even if my UV steriliser destroys all my ferts overnight, I'm still OK as I'll be dosing more than a day's worth of ferts next morning. Correct?
 

ian_m

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which is why a big weekly water change is needed.
Not really, but does have that effect. NO3 etc needs to be in 100's ppm (maybe 1000's ppm) before fish will suffer, but keeping NO3 etc low is fine. Weekly water changes is mainly to remove organic waste build up from the plants (and fish). As tank is high tech the organic waste can't be disposed of fast enough by the resident microbes and if levels are left to build up algae will very quickly move in to dispose of the waste for you. I notice increase in BBA on the plants if I skip a water change (or two).

So even if my UV steriliser destroys all my ferts overnight, I'm still OK as I'll be dosing more than a day's worth of ferts next morning. Correct?
The chelated compounds in the micro solution will quickly become unchelated in the presence of strong light, even more so with UV. So if you insist on using a UV steriliser to correct planted tank water mismanagament issues :)cool:, not a fan of UV as not really needed in planted tank) make sure it is only on when macros are dosed as it won't affect macros. Maybe off then for 24hours after micros have dosed.
 

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