Lighting in 75 Gallon Tank

[cbster]

I have a light fixture from Catalina Aquarium http://www.catalinaaquarium.com/prod...c40d21f14f2ae7 and i have two of the three lights on for 7 hours a day but the
ludwigia arcuata in the tank only has leaves half way down the stem. So that tells me not enough light getting to the bottom of the tank. With two of the lights on there should be enough light for the tank or am i not thinking right. I dose ei method, have pressurized co2, sms substrate, and quite a few plants. Light bulbs are 2 6700k and 1 10000k currently running 1 6700 and 1 10000. So my question is should i turn the third light on or would that be to much light?

 

[mfield4]

I would run them on a cycle, with the 2 6700k bulbs going for 10-12 hours and the 10k bulb going maybe 4 or 5 hours in the middle....

Just my thought though, I am no expert at all. I am sure someone else will chime in

 

[Riiz]

How high are the lights suspended over the substrate and do you have any carpeting/foreground plants currently. If so, how are they doing?

 

[tanker]

Considering that you already have CO2, and ferts and that the bulbs are only 54watts per bulb, you would need all three lights to be on.

 

[TheFishBoss97]

Considering that you already have CO2, and ferts and that the bulbs are only 54watts per bulb, you would need all three lights to be on.

+1

:iagree:

 

[cbster]

the bulbs are 17 inches above the substrate. I have cryptocoryne parva and it is not doing well at all it is green but it is not growing at all. It has been in the tank a long time with no growth. The light fixture is a t5ho.

 

[Cookieman00x]

Use all three lights, its only going to be 2.16 Watts per Gallon, which is just going to be just enough for a co2 injected tank. What kind of timing do you have for your Co2; or is it on all the time?

 

[cbster]

I was under the assumption that you can't go with the wpg rule with t5ho lighting. All the information i have read said three lights would be to much for a 75 gallon tank. My co2 is on a ph controller.

 

[jetajockey]

I was under the assumption that you can't go with the wpg rule with t5ho lighting. All the information i have read said three lights would be to much for a 75 gallon tank. My co2 is on a ph controller.

That is correct.

 

[mfield4]

Theoretically the watt per gallon rule applies to regular fluorescent lights. T5HO are roughly double that of fluorescent I read somewhere, and you probably want to shoot for 2 watts/g.

That said, 2 bulbs would put you at 108 watts of T5HO, about the same as 216 watts of reg. fluorescent lighting, = 2.88 w/g

I am running 2x65 watt compact fluorescent lights on my 75g and it is working great for me.