WPG and CO2/no-CO2 in Smaller Aquaria - The Planted Tank Forum
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post #1 of 7 (permalink) Old 08-13-2005, 04:06 AM Thread Starter
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WPG and CO2/no-CO2 in Smaller Aquaria

Is there a good guideline for how much light is too much light for smaller non-CO2 tanks?

I have read about sucess with 55W over a 20H with just Flourish Excel while in the lighting forum someone said that 65W over a 20H requires at least DIY CO2. Is there really such a fine line?

At what level of light will algae control be impossible?
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post #2 of 7 (permalink) Old 08-13-2005, 11:59 AM
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Thats a tough one because WPG in smaller tanks can be achieved in different ways.
I will say this...if a single bulb's "intensity" is high as opposed to using two lower watt bulbs to achieve the WPG then you may need CO2.
BTW...CO2 is beneficial in all aquariums...it is a just a necessity in high watt tanks.
1 - 36W Compact
2 - 18W NO flouro's

...both add up to 36 watts of light but the growth rate and demands will be much higher with the single compact bulb through intensity and you can grow more varieties of plants...
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post #3 of 7 (permalink) Old 08-13-2005, 08:04 PM Thread Starter
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I guess a better way to word my question is: At what light levels does the low-tech method start to break down for smaller tanks?

Let's stipulate that we have three PC bulbs to pick from (36W, 55W and 65W) and a 20H aquarium. Could you sucessfully do a low-tech, no-CO2 tank with any one of those three bulbs?
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post #4 of 7 (permalink) Old 08-13-2005, 09:35 PM
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light drives the plants

Because light drives the plants, causing them to require more nutrients (N, P, K, , traces and Carbon) you have to give them that or else they will fail in one way or another.

I had a 20H with 55 watts and very low input of DIY CO2 via a gelatine mix and it was fine. It was also very overstocked with fish and I worried about it a lot when power went out or the tank temp got high. The same tank with 36 watts would have been less of a concern and probably would have been fine with Excell and no CO2.

But, you can lower the lighting by adding driftwood that stains the water, by letting the glass get dirty with water splashes, by raising the light up a bit to increase distance. Or replacing the bulb, for many ballasts can run 55 or 36 watts (but check with someone who knows for sure!)
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post #5 of 7 (permalink) Old 08-14-2005, 09:22 PM
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I have both a 29 and a 20 L at 2 wpg. Both are doing fine, and neither has injected CO2. However, both have soil substrates and the 29 has Excel added three times a week to control BGA.

I have a 10 with 1.7 wpg and no extra CO2 and some of the plants are doing great. But some aren't.

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post #6 of 7 (permalink) Old 08-15-2005, 12:22 AM
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I have used all three bulbs in 20gal tall tanks without CO2 as well as with CO2. I find with 20gal tall tanks its more of light penetration then w/gal. What I mean is I run two 20gal side by side with a All Glass 48" CF 110w/ These tanks are low tech. I only use Kent Pro Plant. Take the same take with 55w cf with AH reflectors and the tanks will need some kind of CO2 injection to balance the CO2/ watts/gal. When setting up light/penetration its a balance with CO2. IF you keep 2w/gal with cheap reflector your CO2 demand is lower then using very good reflectors.

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post #7 of 7 (permalink) Old 08-15-2005, 12:53 AM
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I had a 20h setup with flourite substrate and 130w of CF (coralife 65wx2 aqualight deluxe). I could not control algae without the Co2. It was just a necessity! Now on the other hand I had 2 18w NO's over the same tank before the CF fixture and had absoultely no problem with algae. I did however have a problem getting anything to grow in there 'cept for some crypts....
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