Trouble Raising Coral in 30 Gallon Aquarium

[LegendLand]

Hello, i have raised corals for about 5 years in a 55 gallon tank.. soft & lps corals... Last year i decided to set up a small 30 gallon tank for some zoanthus, Hammers & mainly sps..some xenia was later added..so on.. it done great for 6 months or so...but recently its been nothing but trouble... 1st SPS corals would not survive..i tried everything but nothing worked...then some type of black stuff started growing on my rock...the rock i used was dry non-live rock with some Live Rock from my old aquarium. after about 7 months the dry rock was covered in some type of black stuff its almost like they were painted.. then my Hammer coral started to not expand unless a fresh water change was done.. recently i tried some SPS agian..the porites & montipora's are doing great & showing growth...but most others die away, with some still alive.

is it because of so many corals in a small aquarium ?
Should SPS be in an SPS only aquarium ?
Could it be that black stuff on the rocks ? if so what is this stuff ?

ive asked everywhere with little to no results..i hope someone here can help me..thanks

my Water parameters are

Calcium - 400
Alkalinity = 8-10 dKH
PH = 8.2
S.G. = .23 - .26
Ammonia =0
Nitrite = 0
Nitrate = 0
Phosphate =0
Dont test Magnesium & Iodine

i use about 7.oz of carbon & its changed every week.
I use R/O water with Instant Ocean Salt
I have a 150w 10k MH
Flow is moderate to high

Corals include

Xenia
Zoanthus
Favia (Large)
Hammer (Large)
Porites (Yellow Encrusting)
Porites (Green Branching)
Red Chili coral
Acropora
Stylophora
Montipora Digitata
Toadstools
Mushrooms
& Cabbage Leathers

 

[dfs/la2]

LegendLand,

We are sorry to hear that you are having difficulties with your tank and we would be more than happy to further assist you. However, we have a few more questions regarding your set up and ask that you contact our Technical Support Department at 1-800-334-3699 extension 225. It would also help if you are able to email a picture to us at TechSupport@DrsFosterSmith.com so we may view the placement of these corals.

Gwen S.
LiveAquaria
Drs. Foster and Smith