I have some Ferrous sulfate tablets I got at a health food store.
They have 65mg of Fe++ per tab. My tank is 50gal=200l=200kg, so one
tab should raise the Fe by about 325ppb. I measured my iron as
negligible so I added half a tab and measured after 12 hours. Still
negligible. Added another half, wait, still neg. Another half,
wait, sn. Added a dose of micronutrient mix (incl. iron), wait, sn.
Another half, wait, sn. FIVE tabs and a big mn mix dose later, the
iron starts to show. My kit will resolve down to around 20ppb, so I
know it was really low. I also tested some high Fe water for
What it looks like to me is that the plants had a big Fe debt and as
I added Fe, they sucked it up (at least for a while). Does anyone
have any measurements or experiments or experience to confirm that
such a thing is possible? Dave
Dave Gomberg, Experimenta San Francisco CA USA gomberg at wcf_com