I'm familiar with FengShui, but you will have issues with that many fish in a 40, UNLESS you have a sump. The sump gives you more water volume and gives you a place to put more LR so your biological filter is much bigger than without.
I've got a 40b with a 20 gal sump but my total water volume is still only about 40 gals actual water. I've got 7 fish currently in my DT they are as follows:
Cherub Angel
Mocha Ocellaris pair
Midas Blenny
Royal Gramma
Matted File Fish
McCosker's wrasse
I had a Hector's goby but one day he never showed up again. I think it was an older fish as it was full size when I got it and I had it close to a year. Sad to see him go and I'm now looking for another addition, maybe two. My tank is also very heavy LPS along with two BTA's, a few leathers and a few SPS.
Even with my having 7 fish currently my system can handle the fish waste very well, but it's due to having a lot of LR, 2-3 inch sand bed and a skimmer, and regular water changes. What you have to watch out for is high Nitrates! I honestly wouldn't even think of trying to keep 9 fish in this tank without a sump and I've had many fish and tanks in the past.
Now this isn't to say that you can't have even a dozen very small fish in the 40, but you need to figure out what fish you want first, then design the waste removal around that. This isn't something I would recommend to someone new to the hobby.
Start by reading the sticky with the red arrow called Setting Up. There is everything you need to know in that link. After you read up on it come back and ask questions that you might have.
Good Luck to you and your saltwater journey! Welcome to Reef Central :thumbsup:
