Anubias yellowing
 

Many of my anubias leaves are turning yellow on multiple plants. I recently replaced my stock dual t-12 fixture with a shop light that has four t-8 bulbs. it's this fixture:
Shop Utilitech 3" Utility Fluorescent Lighting at Lowes.com

I thought it was a lack of nutrients at first so i've been dosing flourish for the past couple weeks and the yellow continues to spread. It's about a 90 gallon tank, about three feet tall.

Do you know the Lumens and wattage of your T8's (didn't see it on the specs)? If this has started to happen after your switch then I'm wondering if your new lights are not adequate enough for your anubias.

Its just the opposite. The leaves of the anubias are turniing yellow bescause of too much light. This plant does best with low lighting and since this has happen after you upgraded your lights to more lighting this goes along with that. My sugggestion would be to add some floating plants to shade the anubias.

Correct. As noted in the profile, yellow spots indicate too much light intensity. This is a shade plant. Does best under overhanging larger plants like swords, or with floating plants. Being slow-growing, not to fussy on nutrients but does need them, so Flourish Comp or similar once weekly will suffice for this plant.