How much O2 do plants really need?

fablau

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Hello here,
After my termites fumigation success:

http://www.barrreport.com/showthread.php?t=17533

I have discovered that my plants have grown a big deal during the 48 hours fumigation, due probably to the added O2 via air stones. Yes, despite lights have been off for 48 hours, my plants have grown like crazy, in just 48 hours: Hygros grew over 3 inches, Cabomba grew about 3 inches, Rotala grew like a weed, and some of stems that have been stuck for months, have grown at least 0.5-1 inch. I have noticed a double rate growth due to just adding air!

Considering that during those 48 hours I stopped EI fertilization, co2 injection and turned off lights, as well as added carbon to remove any possible bad stuff coming from the fumigation (and therefore micros must have been also reduced by carbon), the only positive variable left was air pumped from outside for 48 hours straight.

I am then questioning the lack of O2 in my system. Despite I have a wet/dry system, and pretty strong surface agitation, looks like my plants would need more O2, presumably at night. What would you suggest doing? Putting an air stone somewhere (maybe in the sump?) that starts when lights turn off? Or adding a power head to run just at night? And then, how to deal, with degassing? I have already pretty fast degas (when co2 starts, my PH is at 7.05-7.1, at the end of the photoperiod the Ph is around 5.9, and I know my water, fully degassed, is at around PH 7.3-7.4)

Anyone else has experienced this kind of O2 issue? How have you improved your O2 mix at night?

Thoughts?
 

toads74

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I've seen a similar effect in my 10g shrimp tank. It was low light/no co2/no ferts. Very small amounts of algae but nothing the shrimp dint keep in check. Also had duckweed in there but it never really did much. I added a conservative amount of co2 during the lighting period and after a month or so saw little difference in growth, but the algae slowed a bit. Out of giggles I added an airstone 24/7 and less than a week after the duckweed exploded, and now about 2 weeks in I'm seeing improvements in some of the other plants as well. Scooping out duckweed by the handful already...which really surprised me since it has access to the air. Best I can figure is the O2 was needed at the roots a lot more that I thought.

- - - Updated - - -

I've seen a similar effect in my 10g shrimp tank. It was low light/no co2/no ferts. Very small amounts of algae but nothing the shrimp dint keep in check. Also had duckweed in there but it never really did much. I added a conservative amount of co2 during the lighting period and after a month or so saw little difference in growth, but the algae slowed a bit. Out of giggles I added an airstone 24/7 and less than a week after the duckweed exploded, and now about 2 weeks in I'm seeing improvements in some of the other plants as well. Scooping out duckweed by the handful already...which really surprised me since it has access to the air. Best I can figure is the O2 was needed at the roots a lot more that I thought.
 

fablau

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How much O2 do plants really need?

Interesting... So you added air 24/7 plus co2 during the photoperiod?

On my side, today I have added an air stone inside my sump, right in front of the main pump intake. I have programmed it to start when lights are turned off until dawn. When it runs, a pretty fine myst is diffused into the tank from the main pump outlets. I wanna see how my plants will react now: plenty of co2 during the day, and plenty of O2 during the night... I will keep you posted!
 

Disco Frank

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interesting

remember though the air we breathe and then the air that is pumped into the tanks is only around 20% o2 and 80% or so N :)
of course this does vary with other gasses present

so could it be the added nitrogen gas?
 

toads74

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yes, it's 24/7 air, then add co2 for about 8 hours during the photoperiod. I had a little surface ripple to start with, so the airstone added quite a bit to that also. My thinking is that providing air all the time should cover the o2 needs of the plants and shrimp better than just relying on the small amounts the plants generate during the day. i say small amounts cause this is a low light tank and plant growth is pretty slow, and plants, critters, etc still consume o2 at night as well.

I had picked up a few crs form Aquatic Experience a couple weeks ago and have like one left, so that prompted me to take a closer look at the tank. I'm assuming they are more sensitive to o2 levels (or so i've heard from the internet rumor mill), so i figured it was worth a try - worst case i'd have bump up the co2 a little. Seems like the rcs are a little happier now too. I want to pick up some more and give it another try, but think i'll wait a little bit and see how it goes. I'm tempted to try it in my 29g also, but it has 2 hob filters and lot more surface movement.

- - - Updated - - -

yes, it's 24/7 air, then add co2 for about 8 hours during the photoperiod. I had a little surface ripple to start with, so the airstone added quite a bit to that also. My thinking is that providing air all the time should cover the o2 needs of the plants and shrimp better than just relying on the small amounts the plants generate during the day. i say small amounts cause this is a low light tank and plant growth is pretty slow, and plants, critters, etc still consume o2 at night as well.

I had picked up a few crs form Aquatic Experience a couple weeks ago and have like one left, so that prompted me to take a closer look at the tank. I'm assuming they are more sensitive to o2 levels (or so i've heard from the internet rumor mill), so i figured it was worth a try - worst case i'd have bump up the co2 a little. Seems like the rcs are a little happier now too. I want to pick up some more and give it another try, but think i'll wait a little bit and see how it goes. I'm tempted to try it in my 29g also, but it has 2 hob filters and lot more surface movement.
 

Whiskey

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I remember hearing that plants do most of their growing at night, and that their reaction to extended periods of time without light is to grow as much as they can figuring they are shaded or something. I know when I did a time lapse of my tank I found the growth was stepped, during the day they didn't expand much, but the first picture in the morning was always another step higher. This happened especially as the plants got closer to the light.

I don't have any references for this, but perhaps someone with more knowledge can help to clarify why exactly it works this way.

Whiskey
 

Tom Barr

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Growth versus elongation are two different things. Keep that in mind.

If I turn the lights off for 2 days, the plants stretch and get longer, but do not "Grow".
 

fablau

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toads74;130978 said:
yes, it's 24/7 air, then add co2 for about 8 hours during the photoperiod. I had a little surface ripple to start with, so the airstone added quite a bit to that also. My thinking is that providing air all the time should cover the o2 needs of the plants and shrimp better than just relying on the small amounts the plants generate during the day. i say small amounts cause this is a low light tank and plant growth is pretty slow, and plants, critters, etc still consume o2 at night as well.

I had picked up a few crs form Aquatic Experience a couple weeks ago and have like one left, so that prompted me to take a closer look at the tank. I'm assuming they are more sensitive to o2 levels (or so i've heard from the internet rumor mill), so i figured it was worth a try - worst case i'd have bump up the co2 a little. Seems like the rcs are a little happier now too. I want to pick up some more and give it another try, but think i'll wait a little bit and see how it goes. I'm tempted to try it in my 29g also, but it has 2 hob filters and lot more surface movement.

- - - Updated - - -

yes, it's 24/7 air, then add co2 for about 8 hours during the photoperiod. I had a little surface ripple to start with, so the airstone added quite a bit to that also. My thinking is that providing air all the time should cover the o2 needs of the plants and shrimp better than just relying on the small amounts the plants generate during the day. i say small amounts cause this is a low light tank and plant growth is pretty slow, and plants, critters, etc still consume o2 at night as well.

I had picked up a few crs form Aquatic Experience a couple weeks ago and have like one left, so that prompted me to take a closer look at the tank. I'm assuming they are more sensitive to o2 levels (or so i've heard from the internet rumor mill), so i figured it was worth a try - worst case i'd have bump up the co2 a little. Seems like the rcs are a little happier now too. I want to pick up some more and give it another try, but think i'll wait a little bit and see how it goes. I'm tempted to try it in my 29g also, but it has 2 hob filters and lot more surface movement.

That's good to know! I also have noticed my RCS more active and I can see them during the day whereas before they were always hidden.
 

fablau

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How much O2 do plants really need?

Whiskey;130980 said:
I remember hearing that plants do most of their growing at night, and that their reaction to extended periods of time without light is to grow as much as they can figuring they are shaded or something. I know when I did a time lapse of my tank I found the growth was stepped, during the day they didn't expand much, but the first picture in the morning was always another step higher. This happened especially as the plants got closer to the light.

I don't have any references for this, but perhaps someone with more knowledge can help to clarify why exactly it works this way.

Whiskey

Yes, plants do grow more during night, when they "breathe". If I remember correctly from my biology class, plants "store" energy during the day and "use" that energy during the night to grow.
 

fablau

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Tom Barr;130981 said:
Growth versus elongation are two different things. Keep that in mind.

If I turn the lights off for 2 days, the plants stretch and get longer, but do not "Grow".

Yes, you are right Tom, my stem plants elongated a big deal because of that. But the fact that some stems of my Rotala "wokeup" after several weeks they were kinda starving, make me think that something triggered that. More O2 could be the explanation. Now I am pumping air at night, and I wanna see how my plants will react and if this "positive" effect will keep going...
 

Whiskey

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I'd be very curious to know, please do post back the results. I'd be even more curios to know if the tanks without a sump have a more profound change than the ones that have a sump.

Whiskey
 

ak24

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Hello guys.


Any update ?


Any proof or information to read about oxygen need by the plants ?