# Is 4 23 watt cfl lights on a 20 inch deep 20 gallon cube high



## pirayaman (Mar 30, 2008)

I have 4 aluminum shop clamp light. Bulbs are 23 watt cfl 6500k and vertically mounted right on top of glass lid 
Tank is 20 inchs deep. So is 4.6 watts per gallon. But is not a regular tank at 20 inches deep. Yes i have read the cfl spiral thread I also have a glass light.

I have also read the par thread. 

I am and obviously so are many people about all cri lumen wpg par k and what everelse 

I think this whole thing should be simplified 

You can have a 100 gallon 12'inch high 9 mile long tank. 

I think simply if I have 20 inches wide 20 inches deep patch of water and want high light 

I think the depth of things confuses the whole idea. 

1 constant is for the most part over 5500 k is clear. I think even if for nothing it makes the tank look better. 

2 lighting makes me insane I have spent 2 weeks at Home Depot and lowes and lfs because of the different types and reflectors and par t12 t8 t5 t5 ho cfl and all that jazz 

I think I have high light. am I right? If all people with 20 inch deep 20 wide patches of water. Who use 4 23 watt cfl 6500k and alum shop/clamp light housings will have high light over this deep of water in this width?


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## GeToChKn (Apr 15, 2011)

You're probably closer to low or medium light than high according to this test.










The waterline in the tank is 7.5, so the 11" above the water is closest to your setup and put it's around low light for a 23w bulb, suspended downward with a decent reflector. With you having 4 of them only over a 20" square surface, you are getting some overlap and the center of your tank is probably closer to med or high as would be the planes splitting your tank into your 4, those 2 lines to split it, they will have more par as well, with the 4 corners with only 1 light covering them will have the least, so plant according to that. As the picture above shows where the highest spots are, with 4 lights I see those numbers being the same, bightest in the middle, but a more pronounced difference because of the overlaps.

With that said, every setup is different and as long as your plants are happy and growing, go with it.


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## pirayaman (Mar 30, 2008)

Ok so I'm returning the 4 8.5 inch clamp fixtures and getting 6 5.5 inch fixtures and 6 23 watt cfl 6500k. The 6500k bulbs are a pain in the arse to find no homedepot no lowes. Really like the clear color they give to water 

Also if anyone wants better reflectors. I saw some called halo at homedepot that are mirror like they are 14 each. But are insane polished. And will fit the standerd clip light size. Would be really nice in a DIY hood.


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## GeToChKn (Apr 15, 2011)

The ones you had may be enough, I don't know now after reading the debate here http://www.plantedtank.net/forums/showthread.php?t=200698 on what is considered high light or medium light. lol.

I have 3x13w CFL's over my 20gal, about 6" above the tank and can grow anything. They are mounted sideways in diy socket style.

I have 2x23w CFL's in a double reptile fixture about 9" above the tank and have to keep the time down a bit or I can grow an algae farm in a week.


With CO2, if you're going for hightech, the polished ones with either 13w or 23w should be more than enough, especially right at the tank surface.

I would go for the best fixtures you can get now though and then you can always alternate bulbs and try different combo's to find what works for your tank. You may not need 23w bulbs with a really polished mirror reflector.


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## FlyingHellFish (Nov 5, 2011)

I have a 23 watt 6500k bulb (also in those reptile fixture) above a 6 gallon PLUS 42 LEDs on top of the water.


But then again, I got Co2 and 3 fat Otos.


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## micheljq (Oct 24, 2012)

From my point of view 4 CFLs 23 watts on your 20H is overkill, unless you want a lot of CO2 and high light (even so it may be overkill).

I have run my 20H tank with 2 CFLs 23 watts for a successfull six months. They were 6" above the tank, 8-10 hours a day. It gave me plenty of light, good growth, and some filamentous algae.

Michel.


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## fishy8807 (Nov 2, 2013)

@GeToChKn, Do you have just the 3, 13w bulbs on your 20? Or are the 2, 23w also on it? I just switched from a 18000k t8 to 3, 13w 6500k bulbs in just regular desk lamps, its also a 20gal tall. Trying to do some higher light plants like HC, but not sure if its enough...I already have a co2 setup n dose ferts as well.


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## acitydweller (Dec 28, 2011)

ive run a 20g high with 3 5.5" shop lamps using 23k 6500k cfl bulbs. This produced high light and likely was overkill but the plants grew really well running at 6.5 hours a day .


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## fishy8807 (Nov 2, 2013)

Awesome! Soo hopefully 3, 13w ones should be alright.. theres not much for reflectors in the desk lamp housings but I was thinking of either getting some little bits of mirror or tin foil and fitting it in there to help, I just like the look of them


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