How much light is enough?

[Rainbowfish Alan]

Hey plant lovers.

So I know you can grow nice plants in a low light tank, but I prefer higher light, CO2 injection and daily ferts.

My question is what lighting you think would be better for a 75 gallon:
108W T5HO plus 34W T8, OR
216W T5HO

I'm tempted to upgrade to 216W but at the same time I don't want to create an algae factory.

[Admin]

216W with T5HO lighting on a 75g might be overkill (depending the height your lights are hanging) unless you want an incredibly high light tank, but if you have a Co2 system that can keep pace, if you are trying for some very hard plants and you don't mind the maintenance, I would say go for it. Remember in theory you can have all the light you want without algae, but only if co2 can keep up (which up to a point it cannot for two reasons: you will gas your fish at a certain point and the hardware at a point cannot go any faster)

108w of t5HO is right in between the medium/highlight range for a 75g (again depending the height your lights are hanging relative to the substrate), so if your looking to do say a carpet of HC or UG this light will still do it, but it may take a veryyyy long time. This amount of light would also be forgiving in terms of co2, algae and maintenance.

A good options might be to buy the 216W of T5HO and (depending on your set up, I don't know if this would be an option for you) hang you lights this way you could raise or lower them depending on your observations of too much light.

[Rainbowfish Alan]

Thanks Admin. The T5 fixture I have is about 3" above the water, and the T8 about 1" above. I'm not sure how to factor this in. Hanging from the ceiling is not an option right now. So given that height do you think it falls more in medium or high light? My gut tells me I am borderline high, but I'm not sure.

[guppyguy]

I am running a 108watt T5 HO light on my 55 gallon and you probably seen my excellent results in my recent before and after pics. I have enough light and light to spare. Light reaches the bottom no problem. So I can grow low growing foreground plants. In a 55 this is consider high light. I would agree with Ryan unless your trying very high light plants 216watt T5 HO might be over kill. And with your light placement in your 75 gallon I would consider your tank moderate/high light.

[Admin]

I agree with the 108w of T5 and 34w T8 I think you are right in between medium to high light on a 75g