Question about lighting wattage in small tank

[BPT]

I thought I read it somewhere that smaller tank have bigger wattage requirement, aka need more than the standard watt/gallon rule. Is it true ? Does 17USG tank constitute a small tank and what is the required wattage for growing plants such as glosso (which is 3watt/gallon standard) in this tank size?

BTW, on this tank I have 1x36 PL, and under this light condition, no plant show active pearling. I did an experiment for half a day by putting a 4x55 PL (overkill ? certainly oversize ) and it was pearling vigorously in minutes.

[IUnknown]

I've noticed the same thing. I had a 18USG with 36 watt (medium light tank) and didn't get noticeable pearling. I now run it at 36x2 and get a lot of pearling.

[vinz]

Think about this.

12USG tank... 3WPG = 1x36W
24USG tank... 3WPG = 2x36W

Imagine you only have one plant in the middle of each tank and both the same height. The light(s) are positioned above the plants.

In the 12USG, the plants only get 1 x 36W of light above them. In the 24USG, they get 2x36W. The height diff for either tank is only a few inches and negligible IMO. The area diff is not a real factor here as there is only one plant placed dead center.

Make your own conclusions.

Personally, for a tank 1.5' tall or shorter, I'll consider 2 rows of PLs as high-light. From 1.5' to 2' tall, 3 rows of PLs.

[juggler]

There was a study made on Amano's tank lighting. Not sure if you like the idea.
See Lighting as a Function of Tank Size in the Aquaria of Takashi Amano

[BPT]

Thanks guys for the info, I sort of still not sure of whats going on with the lighting mystery. I finally settle the tank with 2x55W PL, which gives it about 6.5Watt/gallon and the plants bubbles.

[bclee]

[quote:de09ca2bce="BPT"]Thanks guys for the info, I sort of still not sure of whats going on with the lighting mystery. I finally settle the tank with 2x55W PL, which gives it about 6.5Watt/gallon and the plants bubbles.[/quote:de09ca2bce]
WARNING: 6.5W/gal gives you bubbles... but it will soon give you algae problem if you do not get your CO2 and fertilisation right.

BC

[dts_spawn]

i have a 1ft tank with a 9W clip on light. so far, i've not seen any plant bubble. my CO2 is in the right range and i'm adding trace and K. my question is, is my light too weak?

[BPT]

[quote:0432e30728="bclee"]
WARNING: 6.5W/gal gives you bubbles... but it will soon give you algae problem if you do not get your CO2 and fertilisation right.

BC[/quote:0432e30728]

Uhh ohh.. u're right , somehow i didn't think 'bout that. I think CO2 is in range (20+ppm), but I will cut back on the fertilization. Maybe I need to add more algae eater squad too (just 3 SAE in the tank).
Lower water temp will help avoiding algae too right ? any brand info for good low price chiller ?