Your #1 above is exactly what I am running on my 75g tank. This is close to 3wpg but I am also running CO2. I also have it so that all four bulbs are not on for the full 10hrs. On eset comes on earlier and the other shuts off earlier.


You will be overlapping the 2 fixtures over 2/3 of your tank so even though 216wpg comes out to 2wpg, it is actually a bit less since they are not a full 72" across the whole tank. However, even 2wpg is a bit high unless you are planning to use pressurized CO2 in your setup since these are T5 lights. ;)

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--->Pictures of my 75g Amazon tank<----