# Diatoms and the Urea cycle.



## BruceF (Aug 5, 2011)

Can someone explain this to me? Does that mean that it is likely that NH3 is involved in an outbreak of diatoms?

http://www.nature.com/nature/journal/v473/n7346/full/nature10074.html
http://www.nsf.gov/news/news_summ.jsp?cntn_id=119439


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## Darkcobra (Nov 23, 2009)

Both of these regard marine (saltwater) diatoms. I assume your interest is probably in freshwater diatoms. In which case I'd say:

Speaking generally, there are significant differences between the two environments, not just salinity. Even if all diatoms share a ancient, common evolutionary origin, there has been significant evolution and adaptation since. So I find it better not to assume direct parallels between the two.

Specifically, the described process appears to be an adaptation to environments that are poor in nitrogen and carbon, like seawater. Even poor freshwater is typically much richer in these elements by comparison, so the importance of this process - if it exists in freshwater diatoms - would be minimized.


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## Phil Edwards (Jan 22, 2004)

If the concentration of silicates in the water is high enough then adding urea may encourage diatoms to grow. That's why setups using quartz/silicate gravel and quartz/silicate bearing rocks commonly have diatom blooms in the beginning. Because urea contains both N and C, it's a good source of nutrients for many protists like diatoms, dinoflagellates, and the more typical algae we get in our tanks. That's also why it's really good for establishing biological filtration.


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## BruceF (Aug 5, 2011)

Thanks for the feed back. 

I get this brown film a lot and I am trying to figure out why. All these tanks are the same and pretty much they get the same treatment. Most of them have play sand but not all of them. They are all either backyard dirt or potting soil. They don’t all have fish however. The tanks without filters or fish don’t seem to have this problem. 

I thought that research suggested the ammonia went in and the urea was the by-product. Seems these people no longer think the diatoms are alga.


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