I only have a small light set up and I never use a fan but it looks like your light source is not fluorescent so it has to be farther away from the plants to avoid burning them with heat. I believe that this may lead to leggy plants reaching for the light.
Here is a pic of my little set up. The plant color actually looks greener than the pic shows but the fluorescent tube causes the pic to overexpose.
20180412_104708 by
Brownrexx, on Flickr
Here is another pic showing the color and the stockiness of the stems better
DSC02108 by
Brownrexx, on Flickr