I'm planning a low-light 54G corner tank with compressed CO2 but no water changes. I'll be fertilizing with GH booster once a week, and a touch of NO3 and PO4. Maybe a few drops of Mastergrow to cover any missing traces. What level of light is best for this setup? One 55W CF, 2 55W CFs, or something in between?

Less is more if you plan on doing no water changes, I'd suggest excel or non CO2 if no water changes are the goal. 3x 20w Triton 20 watt of 2x 24 w T5's would be nice.

Adding CO2 is going to drive the growth too fast and require water changes more often or else a lot of balance and testing.
It's easier as well as more practical to do the water changes.

Now if the water change issue is really a large one, and you want to still be practical and realistic over time, go non CO2.

These paths will lead to long term tank stabiolity and less errors on your part, and there will be many, just be smart enough to minimize them.


Regards,
Tom Barr

Non-Co2 it is then. i can't do water changes because this tank will be in my office and water changes won't be practical.

Is there a benefit to 2x 24 w T5's over 1 55w CF? I already have an extra CF fixture available, I'd like to use it unless there is a specific issue it would cause?

Sure , a lot more even distribution of light and planting.
When you have less light, it's better to spread it out evenly, one hot spot is fine if you plan on only some plant types there and you have CO2 added........otherwise a good plant spread and light spread will minimize CO2 limitation for the plants.

It's not something obivious initially.

But it does make a fairly large difference with respect to algae which like more light under CO2 limiting conditions for plants.

Regards,
Tom Barr