DCMU problems

[Pascal Meunier]

In article <199509150403.AA09060 at sequoia.itd.uts.EDU.AU>,
P.Ralph at uts.edu.au wrote:

> Dear Netters,
> 
(cut)
> The 100 M DCMU is mixed with 1% Tween and 1% ethanol in seawater. 

100 M DCMU???  Try 1-10 *micro*M.  The I50 value for DCMU is in the
nanomolar range!  
Pascal