Conflicting Information on lighting: Could really use some counsel - The Planted Tank Forum
 
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post #1 of 3 (permalink) Old 06-16-2010, 07:33 PM Thread Starter
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Conflicting Information on lighting: Could really use some counsel

Hi,

My 90gal is up and running, today about Day28.
4x55 compact flourescents, AH supply reflector
full EI, CO2, heavily planted, drop checker

Right now here's what I do for my photoperiod:
4hrs 110w + 2hrs 220w + 4hrs 110w
(1.2wpg) --- (2.4wpg) --- (1.2wpg)

I am not unread about lighting options, but I have to admit becoming pretty confused about what "level" of lighting I currently have, in terms of both intensity and photoperiod.

This confusion is limiting my ability to make decisions about whether I should change the way I currently have my photoperiod, and whether I should limit my plant choices. Whatever grows with my method and lighting is what will grow. But as issues crop up (plant growth, lack thereof, algae, etc.) it is hard to sort out nutrients vs. CO2 vs. lighting - when I don't have a sense of where my lighting stands.

I would really like a reality check on my lighting. It had been suggested that with 220w CF on 90gal (2.4wpg) that because I was 'upgrading' to good AH Supply reflectors that the "actual" (functional) wpg would be anywhere up to 50% higher, which would put me at 2.9wpg. So with CO2 I figured I could grow most anything but still not be super bright on the lights.

But now it has become more common, and I very much like the logic, to limit burst of 'full' light to the middle of the photoperiod.

So by now doing this: 4hrs 110w (1.2wpg) + 2hrs 220w (2.4wpg) + 4hrs 110w (1.2wpg), I presumably am limiting algae, but 110w (1.2wpg) CF on 90gal for most of the day, seems pretty low.

I do not want algae and hassle.
I do not want algae and hassle.
I do not want algae and hassle.

But I do want healthy plant growth. Healthy does not mean rapid. And I want a reasonable variety of plants to be able to grow well.

So -

(1) where do I sit in general with my lighting ?
(2) is my photoperiod in order, or should the 220w part of the period be increased ?
(3) or, is what I'm doing just fine and let the tank break in for a few months ?

To add to the confusion, I also recognize that new bulbs will have much higher intensity than older bulbs. This tank is still in the "spanking new" category. I have paid attention to many posts over a long period of time, and I am trying to do things the right way, to minimize pain. But on the lighting front I've lost perspective on where I sit and how I should proceed.

* New tank so don't overdo lights. Lower light with short burst to keep algae at bay.
* But higher light to promote strong plant growth because if plant growth is poor algae will win.
* 110w (1.2wpg) CF for most of the photoperiod is pretty low so your intensity should be higher.
* T5/T5HO are really superior, CF are becoming passe.
* But with the good AH reflectors you've really got 'more' light than you think.

I am paying attention, but this is confusing! (and I have to say a tad frustrating )

Sorry for long post. I'd welcome insights and observations.
growitnow

blyxa is crapping out, green hygro growing but pale and poor looking at leaves closest to light, hygro corymbosa siamensis hasn't grown literally at all in 3 weeks, heteranthra zostifolia has really not done well at all, grown little and fallen apart, GSA beginning to appear. So now I'm beginning to trouble shoot.


https://www.plantedtank.net/forums/li...ens-watts.html

http://www.aquabotanic.com/lightcompare.htm
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Last edited by growitnow; 06-16-2010 at 10:15 PM.
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post #2 of 3 (permalink) Old 06-16-2010, 07:51 PM
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I have way less light than you do in my 90 gallon, and a way shorter photoperiod. I have pressurized CO2 which I turn up as high as I can get it (without burping it away) and leave it on 24/7. I get some bba which I have to fight but not too many algae issues.

I would be proud as punch if I could run as much light as you do without algae taking over the whole thing. You should be pleased with what you have. I would guess you can grow anything you want with that arrangement.


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post #3 of 3 (permalink) Old 06-16-2010, 07:59 PM
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With all 4 bulbs your light level is medium, around 50-60 micromols of PAR. (I'm assuming the bulbs are mounted about as far above the top of the tank as the substrate is thick, so the bulbs are 24 inches from the substrate.) With that much light, CO2 is a good idea. You need to dose all of the macro nutrients and trace elements in non-limiting amounts, the EI method, for example. Since you do use CO2, and use a drop checker to be sure you aren't running much too low on CO2 ppm, and you do use the EI dosing method, light should be your only problem.

The problem you may have with the lighting is the 18 inch front to back depth of the tank. This makes it difficult to get uniform lighting over the entire substrate with the bulbs mounted close together. But, if the 2 rows of bulbs are separated by about 8-12 inches to get better uniformity, the intensity will drop, possibly into the low light range. With the rows of bulbs close together, at least the middle half of the tank's depth will get good medium light.

No question, if you had a pair of 2 tube T5HO fixtures lighting the tank, with the fixtures widely separated, you would have both high medium light and good uniformity. Or with a single 4 bulb T5HO fixture, hanging about a foot above the top of the tank, you would also have high medium light, and good uniformity, plus the ability to do in-tank maintenance much easier.

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