2 months, 2 scutes.... Normal?

[Schism]

I got this squamosa on 10-26-02 and the thing has added almost 2 scutes in that time. That seems incredibly fast, but I am new to clams and especially growth. attached is a picture showing the side. THe light coloration is the new growth, obviously .
THe clam is under dual 175 watt halides, 10k ushios.
I just added 2 vho's to the lighting. Hopefully the clams will be even happier!
So is this a normal growth rate or what?

 

[cromax]

Normal Growth? It depends. What are the nitrate levels in your tank? It has been shown that high nitrates (>5-7) can cause explosive growth rates in clams, compromising shell integrity. The shells grow up more than out (thickness). Knop discusses this in his clam bible.

Check your nitrates. If they're in regular range, your clam is probably just so happy that he's growing like crazy!

 

[Schism]

My nitrates are very low. Since I switched to ro/di water about a year ago they have been ate either 0 or very close to it...