SIck Clown???

[Susie Q360]

I just got a P. clown today and now he has little white spots. I used the drip assimulate method, over a 2 hr time frame wt airration.
Did water tests
Ammonia: 0
Nitrate: 5.0
Nitrite: 0
PH: 8.4
Temp: 85
I did a water change due to the nirate level.
This is my equiptment.
Tank Marineland Flat back Hex 18 gal 24" L x 12" W x16" T

Lighting/Hood Marineland 60hz 50wt\TT Floresent

Filters Whisper 10-30i with biofilter
Biopro SK-40 airdriven Protein Skimmer
Live sand 20 lbs
appx 2 lbs live rock
Heater UL 100 watt

Powerhead Zoomed power sweep 30 gal wt prefilter (rotating)

This is my 4th clown and the other 3 died. Please tell me what I'm doing wrong.

 

[dalilgriffith]

Fresh Water Dip him, and get meds for him immediately.

 

[Susie Q360]

What kinds of meds?

 

[reefman13]

Statements:
#1. Your filter isn't great...
#2. 2lbs of live rock in a tank that is 18g is not enough...
#3. We need a pic of the tank...

Questions:
#1. Are you getting all your clowns from the same LFS?
#2. Can we get a pic of the tank?
#3. Are there any other tank inhabitants?

 

[Susie Q360]

Thanks for the advise Dalilgriffth, I did two freshwater dips 12 hours apart. The spots are gone and he's swimming all over the place, athough he always goes back to the rock cliff. And to answer your questions dave:

1. Yes all are from the same lfs (theres only 3 lfs in a 3hr drive
that I know of and only one of them deals in sw)
2. Of course you can get a pic of my tank.
3. Theres a Coral Banded Shrimp. I had a damsel in the tank
too but it kept attacking the bag so I removed it to a smaller
tank. and plan to take it to the lfs tomarrow.

I just started this hobby back in Feb or this year. So I don't know too much about it. And welcome any help. I also know that 2 lbs of live rock isn't enough but I lucked into what I got because the lfs don't notmally carry live rock. I got what I did in Lexington. I plan to order somemore when I get my 46 gal up and running. What kind of filter would you suggest?