Newbie starting first grow

I have spent some time reading thru the site trying to get ready for my first grow. Love the forum :+1:. I have a 10’x10’x8’ room sectioned off. 10" ac infinity exhaust with 10" Terra bloom filter. I have 12"X12" supply vent cut in to room. HLG 650R light. I plan on only using 5x7 area with 9, 4 gallon pots to start. 6 girl scout cookie 3 wedding cake. I am currently cooking my soil. It is Fox Farm Happy Frog and Coco Loco mix with 4 tablespoons of Earth Dust dry nutrients added in per gallon of soil. Temperature holds great at 72degrees but humidity is at 75%. I believe this is ok for seed but will be a problem later. I am waiting for my dehumidifier to arrive to install as well. Just wondering if anyone has any specific tips for me with the information provided. Thanks in advance for any help!

Soil building is gonna be more complicated than those ingredients. In my experience you are asking for problems later on.

75% RH is fine until you get deep into flower. Just keep airflow high.

I will look more into the soil building. I was trying to start simple and easy with the Earth Dust nutrients. They claim only 3 feedings with their products. Any particular issues later on come to your mind. Thanks for input

The main thing is being buffered to a correct range of PH along with correct amount of salts in soil.

i have to watch your grow. i just got the 650r. i know its not enough to grow all my plants but i have more lights for now.