Why oh why does lighting always confuse me so? Some advice please...

[CrazyCatPeekin]

New tank is 36Lx18Dx25H (weird size, I know). I'm looking to keep this one low tech and don't want to creep into too high a lighting category, but I need enough for the plants. I am hoping to get into a nice medium light range.

Was looking at the 36 inch BLACK SOLAR T5 HO - 2 X 39W form Catalina. Would this be appropriate?

I am also considering holding out for the new Finnex LED coming out next month...but I'll be really annoyed if I wait and they turn out to be not strong enough.

I am going to try to make due with 2 T5NO strips (36" and 24") and some spare LEDs I have laying around so I can get the plants in the tank and out of their buckets until I get something permanent. SO, I don't want to wait too long.

Thoughts?

Thanks!

[Trickerie]

Referencing Hoppy's PAR vs Distance chart, if you could get it around 27" from bulb to substrate, you will be sitting at about 80 PAR, which is the cusp of medium light. If you could get it to 30", that would put you comfortably in Medium light.

[mindfestival]

To give you some perspective, I run two 39w T5HO across the length if my 6ft, 95 gallon, about 2 1/2ft from the substrate, and this gives me medium light.

I remember reading that people use the wpg rule for all different types of lighting, and this gives a false impression.

T5HO's are more powerful than you think, and the last thing you want is to blast the light, throw the system out of balance, and fight the algae that occurs.

A better question would be, how low can I run my might, and keep the system in balance?

You mentioned low tech, consider how you will provide co2, and experiment.

This experimental phase is best done at a lower light!

The T5HO's are good value for money, so I would say go for it, but maybe only run half, then gradually increase the light as you master the balance.

[CrazyCatPeekin]

Thanks both of your for your replies.

I am not planning to supplement CO2 at all on this tank...hence low tech. I have a few CO2 injected tanks running now and I wanted to keep this one simpler.

I am not going to be able to get much height on top of the tank. There is a canopy and I have only about 5.25" to work with. Raising the light isn't going to be an option.

I am running a Coralife Aqualight Dual T5HO 24" Fixture on my 24" high Hex tank and I don't think I am getting quite enough light to the bottom with it. I know it is not as good as some of the other brands. There is no algae problem, but my stems are not as healthy as they should be and I think I will need to kick that light up a bit.

Catalina has written back to me suggesting their 36 inch Planted Aquarium Light 2x39 Watt T5 High Lumen. That fixture has independent switches & plugs, so I could run the bulbs independently and perhaps even play around with the photo period...running a single bulb for a full period and only running the other bulb for a short while...if that is something that would even help.

Oh and one question, when you (Trickerie) reference Hoppy's chart, you site the chart as showing the distance of the light form the substrate. But the chart reads as if it references tank height. Considering that a mere couple of inches can be the difference between low and medium or medium and high, and considering that the substrate can be anywhere from 2 to 4 inches (or more if you have "hills" in some spots), I would think that this could make a big difference. SO is the chart referring to distance from substrate or height of the tank? And, if it is tank height, then what substrate depth is assumed?

Maybe I am overthinking this.

[Trickerie]

The chart references tank height due to the way it was tested. However, the distance is all we are concerned about. 20 inches is 20 inches. I assume 2 inch substrate depth, but you're right, it could be more. However, you only need to reference the lowest spot in the tank. As your plants grow they will be under varying light conditions, and that is logically the same idea as varying substrate depth. Thus, find the lowest part and measure to your bulb. Remember, the chart is for one bulb. If you are running multiple you multiply.

[CrazyCatPeekin]

OK...that makes sense.

So looking at the chart again...If I use the Catalina fixture with its excellent reflectors on my 25" tank with about 3" of substrate and I don't raise the fixture at all, one bulb should put me in more or less the middle of the medium light section.

I think I can probably start there with a fairly short photoperiod or 6-7 hours. Then adjust from there, adding the second bulb occasionally or lengthening the photoperiod or both as needed.

Does this sound reasonable?

Thanks for all your help!

[JackFu]

If you can run a single bulb, that might work out ok. I wish my fixture allowed that. I think you can get legs 4" legs for that light, too, if your canopy allows. That fixture would probably run NO bulbs fine, so that's another option.

[jcgd]

Originally Posted by CrazyCatPeekin

I am running a Coralife Aqualight Dual T5HO 24" Fixture on my 24" high Hex tank and I don't think I am getting quite enough light to the bottom with it. I know it is not as good as some of the other brands. There is no algae problem, but my stems are not as healthy as they should be and I think I will need to kick that light up a bit.

I suspect it is more likely that the high light you have is pushing the plants too hard and they are limited by co2 and/or ferts. Being pushed harder isn't going to help plants if they don't have the resources to stay healthy and grow. You'll have have more stunted plants than before.