Botanicare feeding schedule question, please help

I'm using a Botanicare feeding schedule and I noticed that under the Hydrogarden section it says you're supposed to use Pure Blend Pro Soil in weeks 7-10.

So I'm supposed to put PBP Soil in my hydrogarden? Am I reading that correctly? Seems a little counter intuitive. Anyways, if anyone has ever done this or has a better schedule I would appreciate the help. Thanks

Here is a link to the feeding schedule

http://www.growtech215.com/site/wp-content/uploads/2009/03/botanicare2big.jpg

you dont have to, its just because its higher in phosphorus and lower in nitrogen, which is what you want towards the end of flowering.