# 20 Gallon long- Lighting Level



## hoffmanjj19 (Mar 4, 2011)

I'm still new to planted aquariums, and the area I'm having trouble finding guidelines for is lighting. I've been reading everything I can to try to get an idea of what my lighting levels are, but there are so many factors to consider. I'm trying to grow low to moderate light plants in a 20gal.L. My setup is:

2- 24w HO T5
1- 6,700K lamp
1- 5,000K lamp

Lights 16" above substrate
No C02 injection, but dosing flourish excel due to high hardness and PH and plants heavily leeching bicarbonates from water

Does this sound like a low to moderate light plant setup?

Thanks for the help!


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## susankat (Nov 15, 2008)

change the 5000k lamp for another 6700k. It's pretty close to high light. I would suggest looking into co2 even DIY.


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## BBradbury (Apr 22, 2011)

Good morning hoff...

If you're planning on low to moderate light plants, then you don't need more than 1 to 2 watts of light per gallon of tank size. Your current lighting is more than that.

You've gotten good advice to switch out the 5000 K bulb with another in the 6500 to 6700 K range. But, you really only need one 6500 K bulb. This will still give you more than 1 watt per gallon. Since you have a longer tank, in my very humble opinion, this is enough to grow most low to moderate light plants. 

Lighting for low to moderate light plants is really quite simple. You use bulbs that mimic natural daylight, a bulb close to 5500 K. Bulbs in this range are effective for growing most aquautic plants. They can be picked up at most hardware stores for a few dollars each. No need to go to the expense of high end lighting.

One more thing, be very careful with SeaChem's Flourish Excel. It can damage your more primitive plants, like ferns, mosses and varieties of Vallisneria. My ferns are still recovering after I used it briefly more than 6 months ago.

B


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## hoffmanjj19 (Mar 4, 2011)

thanks for the help!

Susankat- I have started DIY C02, but the C02 level doesn't want to go up. I have a HOB filter that doesnt do much surface agitation, but im guessing my KH is keeping the CO2 levels down. 

My current levels are:
Ph: 8.2
KH: 280ppm~ 15 degrees
CO2: ~3


BBradbury- I'm dosing excel because my Ph is 8.2 and my Kh is so high. Is your water similar to this? I tried and am continuing to try to inject C02, but the level doesn't seem to be rising enough to supply my plants with enough carbon. This lack of C02 is causing my plants to use the bicarbonates in the water as their primary source of carbon, so my vals get covered in calcium from biogenic decalcification. My hope is the continued use of Excel will slow the vals' leeching of bicarbinates.


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## jrman83 (Jul 9, 2010)

I have no clue what you're talking about. Guess I have never read about plants leeching anything in the water.

How do you know your CO2 level? What are you using to test it? Excel will not replace the plants need for CO2. KH will not affect CO2 levels if it is being injected. If you are talking about figuring natural CO2 content based off of Kh/ph, then it does have an affect. That is to say that if my tank is a high kh and I am injecting CO2, the amount of CO2 in the tank will be the same if it is a low kh.


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## BBradbury (Apr 22, 2011)

hoffmanjj19 said:


> thanks for the help!
> 
> Susankat- I have started DIY C02, but the C02 level doesn't want to go up. I have a HOB filter that doesnt do much surface agitation, but im guessing my KH is keeping the CO2 levels down.
> 
> ...


Hello again hoff...

I'm sorry, but I'm going to defer to those on the forum more knowledgeable than I on your CO2 questions. I'm strictly low tech. As far as pH is concerned, my experience is just with livebearers and they generally don't care about the acidity or alkalinity of their water. They adapt to either. To my knowledge marine fish can handle most pH levels as long as the level is constant.

The rest of your post went over my head I'm afraid. But, I'm sure some of the more experienced fishkeepers here have an answer for you.

B


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## majerah1 (Oct 29, 2010)

That light is the same amount I have on my 29,which is considered almost high light on mine.I can grow almost anything,and grow it pretty fast.So I will say I think on a 20 long,you are high light,and would look into the CO2 as well.I know I am having to inject mine with it,and am going pressurized.The initial cost is high,but you will have more control over it.

The best way to check the CO2 level is a drop checker.How are you diffusing the CO2 into the water?Injecting it will do no good unless its actually dissolving in the water and not gassing out.


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## hoffmanjj19 (Mar 4, 2011)

Well i was using the bamboo stick difuser method but gave in and bought a glass/ ceramic difuser this morning. After 6 hours of letting the yeast do their work, my PH has dropped to 7.4! I will update soon as to the success of the properly difused co2.


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## James0816 (Jun 19, 2009)

There's a catch here that hasn't been mentioned. Throw the WPG rule out the window on this tank. It doesn't apply to these shallow tanks. You're already at a level considered to be high light with your existing light. But definately swap out that 5k bulb for a 6700k daylight. Running 2x T5 HOs will be pretty intense for your setup and CO2 will be a much needed addition.

Placing the diffuser right next to the HOB intake and under the outflow will be your best option for diffusion. Some bubbles will get taken into the inlet while others will be disbursed via the current.


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## jrman83 (Jul 9, 2010)

I agree. WPG rule doesn't even apply to T5HO at all. I have the same light on a 29 tall and it is still considered high light. CO2 is needed here, but may be able to get away with it with very reduced lighting period, but my guess is BBA will rule without. The CO2 needed cannot be replaced by Excel. The 16" distance to the substrate is that mean it is mounted on top of the tank or elevated above it? I need to look up how tall a 20L is. You possibly could elevate it more to take away the necessity for CO2.


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## Gizmo (Dec 6, 2010)

Improper diffusion is THE main cause of CO2 not being effective, in my opinion. I'm glad you got the better diffuser.

Your light sounds good to me, keep up the good research and consulting!


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