Your grow guy is correct that Ocean Forest contains a high level of fertilizer compared to other media, but it's still not quite enough as you can see.
OF is too 'hot' for small seedlings, and as with all pre-fertilized media, you should fertilize with caution all the way through... but you still need some sort of plant food. Start out a bit weaker than recommended and work up until you see just a bit of tip-burn, then water heavily on the next feeding (to the point of runoff) and back off to the last point at which the plants were hungrily uptaking the ferts without scorching.

Edit: Shultz isn't the best, but it'll do for now- I would only use it for one or 2 feedings since it has far too much N for a flowering plant, and you are getting close to harvest anyway. All you are trying to do at this point is to keep the yellow from getting much worse, while continuing to put on bud mass. Too much nitrogen can slow the production of buds, so you must use it with caution. It's the first # btw.
stinkyattic Reviewed by stinkyattic on . White Rhino YELLOWING LEAVES Naturally I am a little worried, so I decided to post this, in hopes of some feedback. Have 4 White Rhino ladies.....soil grow w/ 400w HPS in my walk-in closet. Started flowering.....and the first oddity I noticed is it tool a good 2 weeks for pestils to show on a 12/12 cycle (from 20/4) which is longer than any strain I have ever grown. Used FoxFarm Open Sesame (1 tsp to a gallon every other watering) and water every other day, 1 1/2 gallons for 4 plants. Everythiong seemed great. Last week Rating: 5