Required reading: Tropica's article on CO2 and light

Tom Barr

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http://www.tropica.com/article.asp?type=aquaristic&id=142

Please take note, and treat light and CO2 like you would nutrients in context of Liebig's law.
CO2 and light can be limiting in aquariums, in terrestrial systems, this is NOT the case, CO2 is not limiting, and light...well you can control it by shading or adding more with MH's etc.

Still, most aquarist need to understand light and CO2 much more to resolve their management issues with growth and algae before pursuing nutrients. This article gives a good background for this.

It also implies light should be limited and thus maximum light use efficiency is obtained.
They conclude lower light + rich CO2 is the bets management for planted aquariums.

So do I, ADA's light data from the 7 ADA tanks, including a 20# in the contest also suggest the same approach is used.

We all came to this independently, as well as many other aquarist. Something to ponder before thinking/assuming EVERYTHING is about nutrient management. If CO2 and/or light is not tested and measured well, then this can confound everything.

Regards,
Tom Barr
 

Biollante

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Light & CO2 With Other Non-Limiting Nutrients

Hi,

Most excellent. :D

Please note that it was under “saturating” nutrient levels. :cool:

What deformity?

Biollante
 

Farmhand

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Not being the point of the article, however I have a question regarding this quote;

" Aquatic plants usually have access two sources of inorganic carbon: carbon dioxide (CO2) and bicarbonate (HCO3-). Most aquatic plants prefer CO2 rather than bicarbonate because it can be taken up from the surroundings without any energetic expenses and many aquatic plants are not able to directly utilise bicarbonate in the photosynthesis"

Is this why more plants do better in lower PH than high?
 

Tom Barr

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Some folks in general might suggest this since richer CO2 water has lower pH.

But CO2 is what plants want, not pH.
Stick with CO2.

Some plants will use HCO3(or KH).........but only as the last resort when all the CO2 is gone.
And these tend to be the aggressive faster growing weeds only.

Regards,
Tom Barr
 

jart

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Left C;51704 said:
Here it is from their new site
Thanks Left C.
I had wondered for some time whether CO2 would benefit lower light tanks.
Good read.
 

1077

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Did I read this wrong (says after reading three times).
Is suggested,stated, that increased light ,even at very low CO2 concentrations can stimulate growth.
with more light available, less investment is needed in the light utilization system and that the freed energy can be invested in more efficient use of CO2 available in the water even though levels are low.
I know my tank has low level of CO2 ,but also low lighting,moderate fish load, moderate plant biomass and soon to be (sunday). weekly dose of NPK plus trace.
Can one expieriment with slowly ,moderately,,, increasing the light,fertz ,without adversely affecting plants?
Im not talking bout High light ,but the study has me thinking (always risky).
Currently running 36 watt x 2 compact flourecent (sp) bulbs 72 watts, for ten hours over 80 gallon tank (prolly closer to 70 gal substrate displacement)
I also have a fixture that would produce 108 watts of T5 HO that nearly everyone has suggested would be possibly too much for my tank.and so I have not tried it.

OOps! should have specified the current bulbs are 6700 K and T5 bulbs are 6500 K
Is low tech non CO2.
 
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dutchy

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If you want to increase the light, you should be able to compensate for the increased demand in nutrients and CO2. If you're not using CO2 and are having no problems, I wouldn't make any changes. First start adding CO2, then experiment with increasing the light.

regards,
dutchy
 

1077

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Yes, I see the wisdom in this. Having no troubles thus far and little to no algae.
After some more thinking,Perhaps I shall note how the plants react to soon to be weekly ferts .
I will spend my time in the interim ,placing more plants and fishes in the tank.
Am loving the idea of fewer water changes after raising a group of juvie Discus to adult size and how.
Pretty happy with things thus far, and shall try to master the low tech endeavor before tinkering with higher lighting, CO2.,etc.

Cheers, Lee.
 

Tom Barr

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If your goal is less work, few water changes etc.....then stick with lower bioloads for the discus (eg large massive tank, few fish, reasonable feeding).

If your goal is more fish, more feeding etc........then add CO2 and keep the light the same, but now do more frequent water changes.

You are not going to get away well with no water changes and lots of overfeed Discus.
There's a way still, but not the typical submersed plant method, eg, you'll need a lot more emergent growth plants, open top or a refugium style set up, lots of floating plants etc.

Regards,
Tom Barr
 

1077

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Thanks Tom.
My apologies,, I should have noted that the Discus have long ago been Re-homed once they reached adult size.
All of the water changes needed for growth ,waste removal, were daunting and once the fish were adult size,,I sold them to make way for other fishes that interest me.
In hindsight,I should have raised the young Discus in Bare bottom tank,would have made things easier but I did not.
Present 80 gal low tech, houses small fish. Ruby barbs,Tetras,cory's.and juvie bristlenose. Approx 40 fish in all.
If however my efforts with the low tech method are fruitful, I may consider such an endeavor for a planted tank with Discus in the not too far off future, Life is much too short.
No worries, Should I once again decide upon the Discus,, It will surely be Adult fish who don't need the frequent feedings and not nearly as many water changes.

Cheers, Lee
 

scottward

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Did I read this wrong (says after reading three times).
Is suggested,stated, that increased light ,even at very low CO2 concentrations can stimulate growth.
with more light available, less investment is needed in the light utilization system and that the freed energy can be invested in more efficient use of CO2 available in the water even though levels are low.

Sorry if I've missed somethere in the replies above...

I just got around to reading this article this morning. It was interesting to read. I was also confused by the above in the article....

So the article is wrong? Is that what Tom was saying right from the start of this thread? Or is there a tiny bit of leeway where a slight increase in light may slightly boost plant growth without making a corresponding change in the CO2?
 

1077

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scottward;55773 said:
Sorry if I've missed somethere in the replies above...

I just got around to reading this article this morning. It was interesting to read. I was also confused by the above in the article....

So the article is wrong? Is that what Tom was saying right from the start of this thread? Or is there a tiny bit of leeway where a slight increase in light may slightly boost plant growth without making a corresponding change in the CO2?

I am still wondering as well about this statement while keeping in mind the old addage,,"If it ain't broke,don't fix it.
I shall await the response of those with MUCH more expierience. Don't believe the wiggle room would be much ,but to squeeze out some more growth without injecting CO2 would be welcome.
 

dutchy

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You can get more growth using the T5 fixture if you start to use Excel as a C-source. Kind of an intermediate between non-CO2 and a CO2 fertilized tank. I helped people to set up a tank like this with T5's at 1,3 to 1,4 Watt per gallon. it works great and no algae, if you don't keep a long photoperiod, typically 8 to 10 hours.

These tanks get good growth, no algae and like 2 to 3 times more growth than non-CO2. This way you can still do regular waterchanges up to 50% per week.

regards,
dutchy
 

1077

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Dang,, I was afraid this would be the case. In my application (80 gallon),, Excel would be more expensive than CO2 injection over the long haul.
I am pleased thus far with the lazy way, and plants seem to be doing better with the dry fertz.
Thank you.