# Help me decide on light fo 125 gallon planted tank



## Daximus (Oct 19, 2011)

evenstarms said:


> Hi, I am trying to decide on which light and how many watts would be best for my 125. I want it to be low-tech so I do not have to mess with CO2. I was thinking of a coralife or current usa T5 lighting. I plan on mostly having sword plants, rotala sp., pennywort, micro sword and some floating plants as well. This is a SA community tank with wild angelfish, tetras, satanoperca and corys. Any suggestions greatly appreciated.


I think I would go for a 4 bulb T5NO, or a pair of 2 bulb T5NO fixtures simply because your tank is very wide and it would probably be easier to spread the light out with two separate fixtures. 

I have a 90 with almost the same dimensions and I'm running a pair of 2 bulb T8 fixtures...well, shop lights actually, lol. For reference sake 128 watts of T8 qualifies (roughly) for low light in a 90 and I'm able to grow everything well, but I struggle with some carpeting plants. This is what it looks like. http://www.plantedtank.net/forums/lighting/157204-cheap-48-t8-2x32-watt-shop.html

Hope this helps. :thumbsup:


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## evenstarms (Mar 15, 2009)

I am thinking about getting two Current USA Nova Extreme 36" 2x39W T5HO 10,000k fixtures for my 125 gallon. Would these be good? Too much light, too little light. If not, would two 36" Corallife power compact 2x96 watt 6700k be okay. Just trying to pin down which one I should order. Would it be better to get a two bulb or four bulb for the tank? I do not want high intensity lighting, only medium.


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## Daximus (Oct 19, 2011)

Is it a 4 foot tank or a 6 foot tank?


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## evenstarms (Mar 15, 2009)

six foot


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## Daximus (Oct 19, 2011)

evenstarms said:


> six foot


Ahh, got ya...I thought it was 4 foot. If those two I like the Current USA Nova Extreme 36" 2x39W T5HO 10k...although I would prefer 6500-8000k bulbs. I personally don't car for the 10k ones. 

I think your second option would be too much light. 

Are you going to hang them or set them right on the tank?


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## evenstarms (Mar 15, 2009)

I have a glass cover so I will probably just set them right on the tank. Let me ask you how much lighting you think I have with my current lights. I have two 48" Corallife T5NO 2x28 watt with a 6700k bulb and a colormax bulb. They overlap each other in the middle of the tank since they are each 4 foot. What level of lighting would that be? Trying to figure it out all seems very confusing to me. :0| If these lights would be good enough then I will just keep them.


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## Daximus (Oct 19, 2011)

evenstarms said:


> I have a glass cover so I will probably just set them right on the tank. Let me ask you how much lighting you think I have with my current lights. I have two 48" Corallife T5NO 2x28 watt with a 6700k bulb and a colormax bulb. They overlap each other in the middle of the tank since they are each 4 foot. What level of lighting would that be? Trying to figure it out all seems very confusing to me. :0| If these lights would be good enough then I will just keep them.


Trust me...the light thing is a bit beyond me as well. The problem is is that there is never an exact answer. Light height, ballast quality, reflector quality, depth of tank...etc all come into play. 

Right now with what you have I would suggest you are somewhere in the low light spectrum. With the big tanks it becomes a chore to get full coverage front to back and side to side...which is also important. 

Maybe look through the tank journal part of the forum for what others are running on their 125s...cause I don't have enough knowledge to tell you what will work for sure.


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## evenstarms (Mar 15, 2009)

okay, thanks. I will look through the tank journals for suggestions.


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## Daximus (Oct 19, 2011)

72" T5HO 4x6500k 


This is what I would be looking for...it's gonna cost ya though.


http://www.plantedtank.net/forums/tank-journals-photo-album/151796-slammeddc2s-125g-low-tech-dirt-tank.html

This guy is using one...you might ask him about it in the above thread.


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## silvawispa (Oct 11, 2011)

2x 4ft 28W t5 bulbs over a 6ft tank is absolutely minimal lighting.

adding the 4x3ft 39W HO tubes puts you into low light, where you should be able to grow something.

If you have too much light you can always set up timers so you have higher light for just a few hours in the day, if you don't have enough, you can't make up for it by leaving them on longer. Go big, then cut down 

I'm not sure the 10K bulbs are useful, I've always had good results with 6500K.

There's loads of info to read and loads of advice given, almost all of it flawed, including mine. Good luck!


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## Hoppy (Dec 24, 2005)

The tank is about 18 inches front to back depth, and 22 inches high, right? You can get good light coverage of the 18 inch depth by hanging a light a foot or more above the top of the tank, or by putting two light fixtures on the top of the tank, with 8 inches or so between them. For the first option, you need a light that gives you 25-35 micromols of PAR at the substrate, about 32 inches from the light. A 6 foot 2 bulb T5HO light with good quality reflectors and ballasts, like a Catalina Aquarium light, will do that ok. For the second option, you need the same PAR at a distance of about 20 inches. Two pairs of 2 x 39 watt FishNeedIt T5HO lights, in 2 rows across the top of the tank, will work.


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## evenstarms (Mar 15, 2009)

Well, I decided to have Catalina custom make two 36" lights for me. The bulbs are set farther apart than a regular 36" two bulb light to get better front to back coverage. I just went with the 2 x 39watt T5HO so that is about 160 watts of T5HO lighting. The lights will be sitting on top of my glass top. I think for my purposes this should be plenty of light, certainly more than what I have now. It is not going to be heavily planted, mostly along the back and sides of the tank and none will be high light demanding plants. Thanks for all the suggestions.


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## jjp2 (May 24, 2008)

Your light level will be really good. I have 4 T5HO 80W over my 125 and I only run 2 bulbs at a time. I find 4 is way too much.


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## jart (Jan 17, 2003)

Good luck, and post some pics when you have things up and running, especially of the angels.

I am planning on using a Catalina 3 bulb T5HO fixture suspended high over a 125 gallon six foot tank. How far apart will your bulbs be?


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## evenstarms (Mar 15, 2009)

The bulbs will be about six inches apart. I will definitely post pics once I get it all set up. I have a bunch of Rio ***** wild and wild cross angels in the tank as well as four satanoperca mapiritensis.


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## Hoppy (Dec 24, 2005)

evenstarms said:


> Well, I decided to have Catalina custom make two 36" lights for me. The bulbs are set farther apart than a regular 36" two bulb light to get better front to back coverage. I just went with the 2 x 39watt T5HO so that is about 160 watts of T5HO lighting. The lights will be sitting on top of my glass top. I think for my purposes this should be plenty of light, certainly more than what I have now. It is not going to be heavily planted, mostly along the back and sides of the tank and none will be high light demanding plants. Thanks for all the suggestions.


If the lights sit on top of the tank, they are about 20 inches from the substrate. At that distance you should be getting about 40 micromols of PAR, if there was no water in the tank. Because the water in the tank increases the PAR about 10-20%, that would increase the PAR to about 45-50 micromols. I think CO2 would be a good idea with this much light. Raising it about 4 inches should let you do without CO2. (This is based on some measurements of the light from a 36 inch Catalina light.)


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## jart (Jan 17, 2003)

Hoppy said:


> If the lights sit on top of the tank, they are about 20 inches from the substrate. At that distance you should be getting about 40 micromols of PAR, if there was no water in the tank. Because the water in the tank increases the PAR about 10-20%, that would increase the PAR to about 45-50 micromols. I think CO2 would be a good idea with this much light. Raising it about 4 inches should let you do without CO2. (This is based on some measurements of the light from a 36 inch Catalina light.)


I'm confused. The OP is thinking of using 2 rows of T5HO tubes, correct? From the charts that Hoppy has provided, wouldn't that give high light (if the fixture sits on the top of the tank? Sorry if I am being dense.


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## Hoppy (Dec 24, 2005)

Here is another Catalina light like that one, only 4 feet long:










Based on this one, you should get around 60 micromols of PAR, which is getting into the area where CO2 is essential. But, you could raise it about 10 inches and get by without CO2.

Or, for a 4 bulb 3 foot long tank.









For this one, use half the PAR shown, since the OP has only 2 bulbs.


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