Newbie lighting question

[Thorndunes]

I have a 75g tank with a HO light system. I have a 55g converted to a fuge under it. I was having a terrible time with red algae and decided to try an experiment. I have fish only at this point so I took the big light off my tank and put my fuge light on it. That light is the old " one bulb" off my old fresh tank. After a week ALL the red slime is gone. I put the big light back on and now two days later it's already coming back.

Are there any long term effects to using the lower wattage light on my tank? I plan to keep it "fish only" at this point.
I have live rock,fish , and my cleaner crew but no coral.

 

[eddie c]

if it's fowlr, lighting isn't important, i had a 55g fowlr and and two 40w bulbs on it and it ran for years with no problems, but i would look into whats causing the algae to grow i.e low flow, old bulbs, too many nutrients, not enough waterchanges, inadequate clean up crew etc.
from my experience though red slime algae will only grow in low flow areas, i will get it in my refugium only where the flow is slow, but will never get it in the main tank.

 

[sir_dudeguy]

After a week ALL the red slime is gone. I put the big light back on and now two days later it's already coming back.

thats because for one, lighting isnt the issue, and for another if its a new tank this is perfectly normal and will go away in time anyways.

There are other reasons too for cyano, such as high nitrates (common in fish only setups) and high phosphates. Or the water you're using could have high total dissolved solids (TDS).

For what its worth, i wouldnt use the big light just because its more likely you'll be using more wattage which would just cost more to run which is pointless if theres no corals.