need ur opinion....

bienlim

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Nov 16, 2007
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hi everyone, im new to the forum but i have been in the hobby for about 15 years and been grwing plants for about 10 years. like everybody that started growing plants i have some ups and down but i did got the hang of it and now grow pretty decnt plants....but my question is which method do u do???? when it comes to co2 injecting method

1. 24/7 with agitation
2. only on when the light is on with no agitation
3. only on when the light is on with agitation


the reason im asking is i been doin the #2 method with good success for years but recently wondering what other people r doin....thanks a lot
 

VaughnH

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Jan 24, 2005
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If your light intensity is low enough, you won't need a high concentration of CO2 in the water, so you can run a lower bubble rate, and run it 24 hours a day, if you wish - people with DIY CO2 commonly do this. Then, you don't need as much surface agitation, and with DIY CO2, you will want only a small amount of surface agitation.

But, when you start using higher light intensity, you need more CO2 concentration to avoid limiting the plants growth rate by having too little CO2. Then, it is harmful to the fish to run that much CO2 24 hours a day, and the fish need a good concentration of O2 in the water to be able to tolerate the CO2 even during the day, so then you need very good surface ripple, and you need to shut off the CO2 when the lights are off. I don't use all that much light intensity, but I still treat it as if I were.
 

Tom Barr

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Depends on light level also, more light, more CO2 demand, and also fish species and load.

High fish load, feeding, higher light, more plant biomass etc.

More current is not bad, and some surface movement(never enough to break the surface) is good.

You do not lose that much more doing this and you offer a lot better O2 levels for fish. You can run airstones at night to bust up surface, add O2 etc also.

This adds plenty of O2 for 14 hours per day, 10 hours you add CO2.
But only when the plants produce O2..............

Regards,
Tom Barr
 

kcharley

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Jan 21, 2009
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I'm confused. What is the difference between agitation and "some surface movement(never enough to break the surface)". I'm about to add pressurized CO2 to a tank next weekend (my first time with CO2) and am switching to a canister filter to minize surface agitation. Thank you.
 

Tom Barr

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kcharley;33983 said:
I'm confused. What is the difference between agitation and "some surface movement(never enough to break the surface)". I'm about to add pressurized CO2 to a tank next weekend (my first time with CO2) and am switching to a canister filter to minize surface agitation. Thank you.

Aeration is only done at night, surface movement is done 24/7 and it does not lose or degas as much. We want O2 in/exchanged, but to keep the CO2.

At night, we can degas and add as much O2 as we want.

Regards,
Tom Barr
 

kcharley

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Jan 21, 2009
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Tom Barr;33988 said:
Aeration is only done at night, surface movement is done 24/7 and it does not lose or degas as much. We want O2 in/exchanged, but to keep the CO2.

At night, we can degas and add as much O2 as we want.

Regards,
Tom Barr

Sorry if I am being thick here. My understanding is that aeration will cause CO2 loss by disturbing the surface. Thus, when I hear agitation I think of a disturbed surface and CO2 loss. I have read on other forums that canisters, instead of hob's, should be used with CO2 as hob's disturb the water surface and thus cause CO2 loss. Am I misunderstanding what Vaughn and others mean by agitation? Do they mean circulation? Thank you.

Greg
 

kcharley

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Jan 21, 2009
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Okay, I think I have the idea now. It is a balancing act/tradeoff. While less agitation means less CO2 loss, it also means more O2 in the water and less scum accumulation. With pressurized CO2, the loss can be compensated by increasing the CO2 injected. Basically I am just going to have to set it up and adjust as I go. I think the real problem is I am an accountant and sometimes forget that the world isn't a set of numbers that either add or don't add. :)

I was just reading the thread Vaughn linked. I can't get the pictures to display. What am I not doing right?

Thanks again.
 

Tom Barr

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Well, most things in Biology are a simple 2 box model, what goes in, must come out, however, there are transformations etc, this is not that different from accounting really.

There's a maximal trade off between how much you can save for Taxes and how much you can spend and still be happy.

Same thing here, there's a trade off between how much CO2 you waste vs how much O2 you need.

During the day, plants add high O2.
So you do not need much aeration etc, and the CO2 can be quite high, some surface movement helps and good circulation also helps move the CO2 around well. You lose a little CO2 this way, but not a lot. You gain a little O2, but that gain is far more important relative to the small CO2 loss.
During night, there's no need for high CO2, so degas it all and add lots of O2.

There's no trade off then.
Tax free O2.

We lose about 90% of the CO2 we add anyway, increasing the efficacy to plants is not going to happen that easy. You have to risk fish loss and stress to get there.

Adding to this issue, algae and CO2 is very difficult to measure.
So eyeballing it and watching very closely when you are around to adjust the CO2 is critical. Do this slowly and progressively, never all at once and lose patience, then come home to gasping fish or dead fish but a pearling planted tank.

I have not done that yet.

Regards,
Tom Barr