Halimeda

[MJB]

I'm not sure if this is exactly a chemistry question so feel free to bump it out of this forum. I have a Halimeda (spp.) growing really quickly in my refugium, much faster than any of the caulerpas. I was curious about the efficiency of nutrient removal v. caulerpa, and the draw on Ca++ and HCO3-(or CO2) as the Halimeda are calcareous in nature. Oddly enough I do not get great coralline growth in either the refugium or the display tank even though nutrient levels are undectable and dKH, Ca++, and pH are steady as a rock at 11, 450, and 8.2-8.3 respectively.
Thanks-----Mark

[tatuvaaj]

You might find this chemical analysis of Halimeda opuntia interesting:

http://www.lars-sebralla.de/ma_halimeda.html

[Randy Holmes-Farley]

Thanks, Tatu, for that link.

The strontium level in that test is amazingly large. So large, that I suspect a problem, but perhaps it's real. I don't read german well, but they clearly are provoked by the high strontium as well. Silica also seems high to me.

Mark:

Certainly, any growing algae is going to absorb significant amounts of both phosphorus and nitrogen.

On a dry weight basis I expect that caulerpa will contain more nitrogen and phosphorus because it doesn't contain the large amount of calcium carbonate that halimeda does.

Nevertheless, if halimeda is what grows well in your tank, I'd use it! Personally, I've not found it to grow well in my system.