Lack of coraline algae
 

I have a 30gl fowlr that has been set up for about 5 months with about 40lbs of rock. I just recently added 18lbs of dry rock to make it 40 and I have been testing my alkalinity and calcium every other day and neither of them go down or really change. I never really had any coralline algae growth just on 2 rocks and on some shells....Should this be a problem?

My live stock:
B&W Ocellaris Clown
Ocellaris Clown
Yellow Watchman Goby
Longnose Hawkfish
Firefish
Wrasse-not sure what kind it is....one of the flasher wrasses

Invertes:
2 peppermint shrimp
skunk shrimp
camel shrimp

whats your lighting? That could easily be the problem. If your lighting is sufficient then i suggest getting a rock with coraline all ready on it from a friend or lfs.

What are your Alkalinity and Calcium levels?

DKH is 12, calcium is 480. I have one Actinic 420 bulb and the other is what came in it.

Those levels are very good. It very well could be the lack of lighting that is slowing the coraline growth in your tank. Can you post a pic of the fixture?
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Before you worry, realize that it may take 4 to 6 months of aquarium maturity for you to really see coraline begin to set hold. If the aquarium has been set up for this long or longer, then I would say the lack of coraline growth is a sign that something is "off".

One issue could be livestock. Urchins eat coraline. Do you have an urchine in the tank?

Another possibility is excessive phosphate which makes it difficult for calcium to be utilized properly by coraline algae and corals. Give your phosphates a test, both in the tank water and from the source water.

I would explore the calcium situation in more detail, including tests for phosphate, magnesium, and pH. I would even be interested in strontium and iron test results before dismissing water chemistry as the cause of poor coraline growth.

What salt mix & buffers do you use?

For salt mix I use the instant ocean. And I don't use any buffers. I have the calcium A&B stuff but I havent put them in yet because I would just be adding more calcium to the tank.

Ok, lets talk about this a bit. What exactly are you using? At least from what I have seen, the A & B additives are a combination of carbonate buffers and calcium chloride.

Its called Kent marine nano-reefs part a and b