Diatoms and low light?

[GillesF]

I have a question for the algae guru's over here: is it true that diatoms are caused by low light and/or silicates?

My father used to have a low light tank (it's being rebuild at this moment) and never got diatoms except in difficult to reach spots. I'm more likely to believe that diatoms or brown algae are caused by insufficient nutritients (due to high light) or bad water circulation (e.g. my father's tank). I've also been a disbeliever of the "diatoms are caused by silicates" argument. How was this tested?

What's your opinion Tom?

Cheers,
Gilles

 

[dutchy]

Sorry that I'm not Tom, but:

These unicellular algae generally placed in the family Bacillariophyceae thrives in low light conditions. Further, since the cell wall is predominantly silicate and these organisms proliferate in water that has a silicate concentration high enough to support diatom growth. No Si means no growth, simple as that.

Many aquarists find that over time, the diatom growth will diminish naturally though it may never disappear entirely.

Diatoms are either photoheterotrophic or photoautotrophic, neither process involves nitrate, although high PO4 levels promote growth.

Photoautotrophy is most common in lakes, rivers and the home aquarium. As photoautotrophic organisms, diatoms utilize the sunlight as energy to convert carbon dioxide and water into organic compounds. The photosynthetic pigments, chlorophyll and carotenoid, absorb light energy. Carotenoids are the most abundant pigment in diatoms and mask the presence of chlorophyll, which is why diatoms are brown rather than green.

The reason that diatoms seem to proliferate in beginner tanks is simply that high levels of Si caused by new substrate gives them a chance to grow.

Diatoms take advantage of spectrums in the blue and far red. Since these spectra will penetrate the most, it's logic that they will thrive in low light conditions.

You might also want to read: http://www.barrreport.com/showthread.php/3121-Barr-Report-Newsletter-Diatoms-and-Aquatic-Plants

 

[GillesF]

Dutchy

Thanks for the great info, I will change this on my blog.

Cheers,
GillesF