Re: Thread algae

>From: George Booth <booth at hpmtlgb1_lvld.hp.com>
>Date: Tue, 09 Jan 1996 08:46:57 -0700
>Subject: Re: Thread algae
>> From: u7211aa at sunmail_lrz-muenchen.de (Michael Irlbeck)
>> Date: Wed, 03 Jan 96 17:16:34 CET
>> However, there is a persistent problem with thread algae (the green,
>> spider web like, hairy stuff which makes long, well, 'threads') and
>> now I'm out of ideas for fighting them.
>> NO2=n.d, NO3<12.5 mg/l, PO4=n.d, Fe barely detectable (<0.05 mg/l).
>> 7 drops of the daily stuff.
>> I am trying to stay on the low side with the iron, since George
>> reported increased thread algae growth with higher iron levels.
>Do you trust your iron test kit?  I would try reducing the daily drops
>to 5 or 6 for a week or so and see what happens.  The only time we see
>thread algae is when the iron goes over 0.1 ppm (measured with a
>Lamotte iorn test kit). 

The iron test kit is made by JBL. When I used the Dupla
recommended dose of iron drops (12/d for 600 l of
water) I had readings of just below 0.1 mg/l. I haven't
controlled it with any other test. Actually, I have
tried 5 daily drops for a while and the iron was
practically non-detectable under that doseage. With
7/day it's barely detectable. The thread algae still
grew well with 5/day.

>Note: We don't start daily drops until 3 days after a water change -
>the plant tablets also contain enough iron for that period. 

Good idea. I have also thought about removing the plant
species that host most of the thread algae. It's
primarily stuck to the Rotala rotundifolia and the
Heteranthera zosterifolia. Not because it grows faster
on these plants, but it's hard to remove them
completely from them, so it keeps coming back very
quickly. This is essentially preventing me from growing
any fine-leaved plants. 
Maybe I should try another iron test kit. Lamotte isn't
available in Germany, however. Maybe someone at the lab
here has a method?


|                       |                                 |
|Michael Irlbeck        |  u7211aa at sunmail_lrz-muenchen.de|
|Anaesthesiology        |                                 |
|University of Munich   |                  CIS:100277,343 |