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Dissolved Oxygen: Do we need aeration during Daytime?

 




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lamig747
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Aug 3, 2009, 7:55 AM

Post #1 of 84 (14711 views)
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Dissolved Oxygen: Do we need aeration during Daytime? Can't Post

Hi guys,

Wanted to share with you something aquaculture people (farmers raising prawns, tilapia, sea bass etc) take utmost care when looking after their farmed fishes - esp on Dissolved Oxygen. Normally, Dissolved oxygen concentration in ponds fluctuates on a 24-hour basis. This fluctuation is called a diurnal oxygen cycle. Dissolved oxygen increases during daylight hours when photosynthesis is occurring and decreases at night when respiration continues but photosynthesis does not.

Ive seen posts where people claim that they reduce their 'water pump at night to save electricity' and the like and I guess the reason for this post is to actually warn against this practice especially if the pump agitates the water to help produce DO.

Ive also seen many filters that continuously run aerators during the day and IMO, this can be reduced as there simply is a lot of Oxygen circulating around. BUT this is a big requirement at night to keep the bacteria & the fish alive.

In fact one posts Ive read fr the Phils (Pond Disaster (All My Koi's Died)), said it all, the fish kill was noted in early morning after all the pupms was accidentally turned off.

I would encourage members who have DO equipment to validate this by testing at different times of the day (ie 6am, 12 noon, 6pm, 12 midnight).

However, there are situations where DO in the morning decreases like, very hot weather (>34 C), overcast skies/no wind.

Ive attached a table to show the day-night-day-night (dndn) effect to DO levels.

Rgds,
Lamig
Attachments: Oxygen cycle.emf (25.3 KB)


KoiAnswers
Koi Kichi

Aug 3, 2009, 8:59 AM

Post #2 of 84 (14696 views)
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Re: [lamig747] Dissolved Oxygen: Do we need aeration during Daytime? [In reply to] Can't Post

Dear Lamig,
This is a good point that you have highlighted. All plant base (algae and water suspended plant like organism) do photosynthesis during the day so the by product is OYXGEN, but at night they RESPIRE thus consume oxygen i.e. naturally bringing down the TDO level at night.

By then again with the heat and all duirng the day and especially during the hot spell, the water cant retain the oxygen in the water to also cause the TDO to be lower than normal.

4 hours is all it takes after the water pump malfunction before the kois die due to oxygen starvation.



larz1
Veteran


Aug 5, 2009, 3:42 PM

Post #3 of 84 (14590 views)
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Re: [lamig747] Dissolved Oxygen: Do we need aeration during Daytime? [In reply to] Can't Post

I can't think of any good time to reduce aeration. Air pumps are one of the lowest energy consumers in a typical pond and the day/night photosynthesis shift also coincides with the temperature shift which influences O2 levels as well. I say keep the water well aerated at all times and take no chances.


coy
User


Aug 5, 2009, 4:09 PM

Post #4 of 84 (14580 views)
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Re: [lamig747] Dissolved Oxygen: Do we need aeration during Daytime? [In reply to] Can't Post

Hi Lamig,
I have my main pond air pump on a timer that comes on at 7.30pm and off at 7.30am, but the filter bed air pump is on 24Hrs - i see no indication of any problem and been running this for the past few months although the pond is well shaded to keep the temp down so this helps.
The lost most of my koi previously due to water pump failure Frown - i am understandably paranoid now and i have a complete backup system including an automatic UPS suitable for 6 Hrs for the running the water & air pumps, which accords great peace of mind when away from the house Smile.

Cheers

Phil


PH8
Veteran


Aug 5, 2009, 4:25 PM

Post #5 of 84 (14576 views)
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Re: [coy] Dissolved Oxygen: Do we need aeration during Daytime? [In reply to] Can't Post

Hi Bro Phil,

Totally agree with Brother Larry. Ideally, I would try as hard as I possibly can to always maintain TDO levels at saturation point, wherever that may be depending on the water temperature, night and day. Have you ever tested your TDO level? Koi can survive in TDO levels of 4, and even down to 2, but they won't necessarily thrive. I would personally opt to keep all the air blowers on 24/7. But...that's me WinkWink


Cheers,
Paul


(This post was edited by PH8 on Aug 5, 2009, 5:14 PM)


coy
User


Aug 5, 2009, 5:07 PM

Post #6 of 84 (14569 views)
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Re: [PH8] Dissolved Oxygen: Do we need aeration during Daytime? [In reply to] Can't Post

Hi there Paul Smile,
Oops - I forgot to mention the backup pressure filter outlet is piped into the UV system which then dumps the water vertically down a few inches above the pond water level at a rate of 5900 Lts / Hr - so i guess there is a good source of aeration in constant operation.
Cheers

Phil


PH8
Veteran


Aug 5, 2009, 5:13 PM

Post #7 of 84 (14564 views)
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Re: [coy] Dissolved Oxygen: Do we need aeration during Daytime? [In reply to] Can't Post

If you actually check your TDO level, the result might surprise you.SmileSmileSmile


coy
User


Aug 5, 2009, 5:44 PM

Post #8 of 84 (14556 views)
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Re: [PH8] Dissolved Oxygen: Do we need aeration during Daytime? [In reply to] Can't Post

Paul,
DO reading tonight is 5Mg/L @ 27.6 Deg C.
Cheers

Phil


PH8
Veteran


Aug 5, 2009, 5:48 PM

Post #9 of 84 (14554 views)
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Re: [coy] Dissolved Oxygen: Do we need aeration during Daytime? [In reply to] Can't Post

Wah, you got your own TDO meter ah?SlySlySly Curious what it would be during the day when your blower is off but photosynthesis is in favour of oxygen? Is 5 a level you're happy with? Each and every hobbyist has a different objective, so there isn't really any right or wrong.SmileSmile


coy
User


Aug 5, 2009, 5:58 PM

Post #10 of 84 (14546 views)
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Re: [PH8] Dissolved Oxygen: Do we need aeration during Daytime? [In reply to] Can't Post

It is a SERA 02 Test Kit bought from East Aqua - rm45.60, does 60 tests Smile

Will try and test in the morning and again b4 the blower restarts in the evening on Thursday to see the variation.

Cheers

Phil


PH8
Veteran


Aug 5, 2009, 6:30 PM

Post #11 of 84 (14541 views)
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Re: [coy] Dissolved Oxygen: Do we need aeration during Daytime? [In reply to] Can't Post

That would be interesting, yes. We can learn from this.Smile


coy
User


Aug 6, 2009, 2:27 AM

Post #12 of 84 (14517 views)
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Re: [PH8] Dissolved Oxygen: Do we need aeration during Daytime? [In reply to] Can't Post

Test time - 0715Hrs

DO 6Mg / Ltr @ 26.3 Deg C.


PH8
Veteran


Aug 6, 2009, 4:01 AM

Post #13 of 84 (14504 views)
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Re: [coy] Dissolved Oxygen: Do we need aeration during Daytime? [In reply to] Can't Post

I must say, your water temperature is quite low! How do you do it? I don't think you have a chiller, do you? How about bakki shower?


coy
User


Aug 6, 2009, 5:02 AM

Post #14 of 84 (14493 views)
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Re: [PH8] Dissolved Oxygen: Do we need aeration during Daytime? [In reply to] Can't Post

No chiller or Bakki - The pond is shaded from direct sunlight now and i suppose as there was no sun yesterday (hazy all day) and the rainy day on Tuesday the temp managed to drop - i only raise the blinds in the evening and weekends - otherwise they are down.
See attached photo's of before and after.





(This post was edited by thiamhwa on Aug 7, 2009, 4:00 AM)


coy
User


Aug 6, 2009, 12:51 PM

Post #15 of 84 (14446 views)
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Re: [coy] Dissolved Oxygen: Do we need aeration during Daytime? [In reply to] Can't Post

Test Result as of 1730Hrs:-

DO 5Mg/Ltr @ 27.4 Deg C - So nothing really changed from yesterday Smile


PH8
Veteran


Aug 6, 2009, 1:10 PM

Post #16 of 84 (14441 views)
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Re: [coy] Dissolved Oxygen: Do we need aeration during Daytime? [In reply to] Can't Post

I guess the question will still remain that if leaving the airblower on during the day could give the koi a TDO level of 6.5ppm, would you?WinkWink


coy
User


Aug 6, 2009, 1:44 PM

Post #17 of 84 (14438 views)
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Re: [PH8] Dissolved Oxygen: Do we need aeration during Daytime? [In reply to] Can't Post

Sure, no probs Smile


ikankoiku
User


Aug 7, 2009, 9:11 AM

Post #18 of 84 (14386 views)
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Re: [coy] Dissolved Oxygen: Do we need aeration during Daytime? [In reply to] Can't Post

Hi bro Phil and Paul,

I always wonder my DO in my big pond. Still looking for DO test kit. Is Atari, KDF or Arowana selling it? Don't have any idea where is East Aqua. Can you give me a rough direction? What is the accuracy of this test kit?

Since I am not sure of my DO, I use 3 Resun 100 air blowers for my 33ton pond and Hi Blow 80 for my 7 ton pond. It runs 24/7. Do you measure it at the furthest end from the aeration or middle? What about your temp, do you take reading at the middle of water level?

I believe, photosynthesis rate will be better for smaller pond as the algae on the wall and floor of the smaller pond has better significant effect on total volume of water. But again, surface contact of bigger pond is better than the small pond. I guess, the best is to have big surface pond which is not to deep. But all this effect will be reversed at nightCrazyCrazyCrazy. Till I know what is the saturated level of DO in the pond and the actual DO, not really dare to reduce the air blower to save the electricity. Hopefully I can do this test in the very near future.Thanks for your info.

Regards

IKK


PH8
Veteran


Aug 7, 2009, 9:17 AM

Post #19 of 84 (14384 views)
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Re: [ikankoiku] Dissolved Oxygen: Do we need aeration during Daytime? [In reply to] Can't Post

Bro IKK,

I don't use test kits because I'm colour blind, so I will leave this to Bro Phil to answer...Smile From what I understand, these test kits are not that accurate, so just use them as an indication only.


coy
User


Aug 7, 2009, 10:13 AM

Post #20 of 84 (14371 views)
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Re: [ikankoiku] Dissolved Oxygen: Do we need aeration during Daytime? [In reply to] Can't Post

Hi IKK,
East Aqua is the company who provides the aquaruim section of Pets Wonderland in Mid Valley Mega Mall, and also within Pet Safari in Ikano Power Centre - i got the kit at Mid Valley.

In regards to it's accuracy, i don't know but it is a colour chart test and these are as Bro Paul says "indicative" only.

I take the reading at the far end away from my 6 airstones and as my depth is only 2 ft i take the water from about 1 ft down.

Cheers

Phil


PH8
Veteran


Aug 7, 2009, 10:24 AM

Post #21 of 84 (14369 views)
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Re: [coy] Dissolved Oxygen: Do we need aeration during Daytime? [In reply to] Can't Post

Hmm, makes sense. Your TDO level is not too bad because it's a shallow pond. Shallow ponds tend to have better TDO levels because their ratio of air-water interface is higher compared to a deeper pond (whether same footprint or same volume), all other things being equal. The blower which you normally switch off during day, does it drive all 6 airstones?


coy
User


Aug 7, 2009, 10:47 AM

Post #22 of 84 (14360 views)
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Re: [PH8] Dissolved Oxygen: Do we need aeration during Daytime? [In reply to] Can't Post

Yes, but there are another 4 in the filter chambers (on 24/7) and not forgetting the UV outlet.
Photo attached.




(This post was edited by thiamhwa on Aug 7, 2009, 11:04 AM)


coy
User


Aug 7, 2009, 12:02 PM

Post #23 of 84 (14337 views)
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Re: [PH8] Dissolved Oxygen: Do we need aeration during Daytime? [In reply to] Can't Post

The DO reading just now was 5 @ 27.2 Deg C, but this was most probably caused by the thunderstorm we are having here in Seri Kembangan :(
Will carry out the test on Saturday morning before the water change.


ikankoiku
User


Aug 7, 2009, 12:20 PM

Post #24 of 84 (14332 views)
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Re: [coy] Dissolved Oxygen: Do we need aeration during Daytime? [In reply to] Can't Post

Thanks for the info bros. Will get it once I get back. Cheers.


archer07
Novice


Aug 7, 2009, 3:55 PM

Post #25 of 84 (14282 views)
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Re: [coy] Dissolved Oxygen: Do we need aeration during Daytime? [In reply to] Can't Post

 
wow , very nice water temperature . can bring up DO more easily.

might share some pond photos with koi ?

thank you so much.
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http://justiceforbenghock.blogspot.com/


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