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Thanks to the charts I can now confirm that I was sunburning my plants and fish :icon_cool

I shut down 2 of the T5HOs and will continue with just 2 now and those alone would give me ~100 micromols at my current height of 23" from substrate.
 

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Ok im newer to planted tanks and trying to learn as much as i can as i slowly build up my 75g tanks. Right now i am trying to figgure out my lighting needs. So here is my question with only being able to get t5no lights at 2x28watts how many would i need to buy to put me at the higher end low to low mid mid light range if my substrate will be at about 20 to 22in from my light with basic reflection ie white paint as the min but more likly Aluminium coil stock lind custom hood. I know that i should try for a better light scorce but because of where i live and cash flow it has limited me in what i can buy at this time.
 

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You should be fine with one 2x28 per tank to get low to med light

Edit: i meant with a good reflector, see Hoppy's comments below
 

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Discussion Starter · #46 ·
Ok im newer to planted tanks and trying to learn as much as i can as i slowly build up my 75g tanks. Right now i am trying to figgure out my lighting needs. So here is my question with only being able to get t5no lights at 2x28watts how many would i need to buy to put me at the higher end low to low mid mid light range if my substrate will be at about 20 to 22in from my light with basic reflection ie white paint as the min but more likly Aluminium coil stock lind custom hood. I know that i should try for a better light scorce but because of where i live and cash flow it has limited me in what i can buy at this time.
That is actually a difficult question to answer. Those charts for T5 are based on the light you get with typical T5 highly polished aluminum reflectors. You can make a lot of assumptions about what percentage of the light comes from reflection off the really good reflectors, and use that to guess at how much PAR you would get without any reflector, then add maybe 10-20% more for the white painted, but flat reflective surface. What you would end up with would be very inaccurate, and probably worthless.

Or, since 28 watt T5NO bulbs are about 48 inches long, you can assume they produce the same light as a T8 48 inch bulb, but use less electricity to do so. That is probably a better guess. Then I would assume they produce perhaps 20% more light than that due to the smaller tube size, giving what should be a brighter light. Doing that, my guess is that 2-28 watt T5NO bulbs at 20 -22 inches with a flat white reflector would give you low light, just barely within the range for low light. Using aluminum foil instead of white paint would slightly increase the amount of light, because white paint is a very good reflector surface, almost as good as aluminum foil. But, it would be worth doing since it might be enough improvement to get the light intensity well within the low light range.

You could further improve this by using a curved reflector surface that surrounds the tubes on 3 sides - like a section of rain gutter, for example. Then line that with aluminum foil. I doubt that this would get you to medium light, but it might.
 

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i am able to get coil stock that his polished aluminum like the kind that people would use around a chimney for the rain pan . The type i can get comes in from 14 to 20in wide by 10 ft long. i have done some construction and i am use to having to bent it at slight angles and even to curv it. i could curve a piece behind the lights as a makeshift relflector. I am planning to get more of the 2 set lights atleast 2 more so that wold put my at 3x28wttsx2 or about 160 watts over my 75 g aquarium and that woud put me at about 2.3 wpg i know that wpg is not a good mesurement to go buy buy.
 

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You might want to move the figures on Page 2 onto the first post, Hoppy. I like that graph better than the first one. Would be good for newer people, since they will prob look at the first post for sure.

Seriously though, when I read these threads, it was like a revelation for me. The amount of lighting misinformation out there staggers the mind. When I was new to the hobby, people had me convinced I needed like 4 wpg. Of course I ran out and bought a high-powered T5HO fixture and plopped it directly over my 16"-tall tank.

I wonder how many people are driven out of this hobby due to following such bad advice, as they watch their entire tank become a mess of algae? We need more people like Hoppy!
 

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Im a newbie and dont have a very scientific mind, but your chart was very easy to understand Hoppy - thankyou! Apparantly, I have no light in my tank :icon_eek:

My water depth is about 20" and I have 2 x T8 (30w each) lights fitted to the underside of the hood. Im not too worried about this - my fish are happy and the plants are growing.

My question is where do LEDs come into all this? Im planning on getting another tank after the New Year (approx 120cm wide x 40cm deep x 50cm high) and I love the "shimmer" effect you get from LEDs. I also understand that LEDs are more intense than T5s so I should have better plant growth. I plan on four TMC GroBeams (two at the front so they cover the full length of the tank, then the same again at the back).

Any comments or opinions???

Thanks.
 

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I found this thread to be very helpful--and money saving! Now I know that I only need 2x54w T5HO bulbs for my 75g to be the high light tank I want. :biggrin:

Do you think it's just a marketing ploy to make the 4, 6, or 8 bulb T5HO fixtures?

-Lisa
 

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Discussion Starter · #55 ·
I found this thread to be very helpful--and money saving! Now I know that I only need 2x54w T5HO bulbs for my 75g to be the high light tank I want. :biggrin:

Do you think it's just a marketing ploy to make the 4, 6, or 8 bulb T5HO fixtures?

-Lisa
T5HO fixtures are usually made for reef tanks, where a lot more light is used. That market is a lot bigger than the planted tank market, too. So, manufacturers make lights that are appropriate for reef tanks, with multiple bulbs, actinic bulbs, 12000K color temperature bulbs, etc. Only occasionally do you see fixtures made just for planted tanks, and they almost always have only 2 bulbs.
 

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Hi Hoppy,

Do you think I'll be OK with my 2 bulbs t5ho raised 30" above substrate ? No co2, just excel......... very heavy planted tank since yesterday
 

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Hi Hoppy,

Not sure if you missed my question?

Was wondering how LEDs compare with the other lights you mention?

In particular, TMC GroBeams?

Many thanks :icon_smil
 

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Discussion Starter · #60 ·
Hi Hoppy,

Not sure if you missed my question?

Was wondering how LEDs compare with the other lights you mention?

In particular, TMC GroBeams?

Many thanks :icon_smil
Sorry, I just forgot to come back to it.

LEDs aren't like other lights. For one thing a single LED doesn't produce enough light to work on any but the small nano tanks. So, you always need to use an array of LEDs to do a good job lighting a planted tank. For the moment, this, http://www.plantedtank.net/forums/diy/84212-designing-building-led-fixture-22.html#post1102937 is the best I can come up with for picking LED lights. And, so far I haven't seen an LED light fixture that I think is a good planted tank light, so to use LEDs you have to DIY one.

That GroBeam 1000 version is only about 8 inches square, so it is probably only effective on a 12 inch maximum depth (front to back) tank, and a 55 gallon tank, for example would need about 5 of them. I don't know what they cost, but I suspect 5 of them would empty most of our hobby budgets. Price has always been the problem with LED fixtures.
 
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