Peter Breed wrote:
Like many the first time I saw fertiliser for ponds I thought thats a
bit expensive I but at least it'll do the job. Later I read in various
places including rec.ponds that fish food adds N(itrogen) and
P(hosphate) leaving the K(alium/potassium/potash) so this was the only
thing in the way of soluble fertiliser to add. Hence I bought some
potassium sulphate which I have been occasionally adding to the pond.
However I also noted that the commercial product also contains iron and
some other nutrients. So I was down the garden center and spotted
something called sequesterene which in big friendly letter says cures
iron deficiency, so I bought it thinking the chelated iron would
substitute for that in the commerial pond fertiliser. However when I got
it home and read the small print the sequesterene says "Harmful to
aquatic organisims, may cause long term adverse effects in the aquatic
enviroment"
Sorry for the long winded intro but my question is whats going on? Is
this a dosage thing, the different form of chelated iron, maybe some
other ingredient that might cause a problem. Most of the active
ingredients seem similar if in different proportions to that in my water
lilly spikes. The only difference seems to be the chelating agents.

Has any one had problems due to iron or manganese shortage?
My lillies didn't grow as vigoursly last year as previous years, so I'm
trying to get a handle on what might be going on.
Peter Breed

The name Sequestrene was familiar enough that I got curious and went
searching for it in the aquatic plant forums I frequent. Turns out
there's not much information at all. A few Europeans mention using
EDDHA-iron in aquariums, and nobody has said it killed their fish. It
could certainly be a dosage thing but that label is pretty scary. :-/

I found a lot of mention of Chempak Trace Elements from UK aquarists.
The Chempak mix has the cheaper, more common EDTA iron. Maybe you could
find that brand since EDTA chelates are a bit more tried and true.

Iron/mangnese shortage is hard to miss. The plants get chlorotic with
pale or yellow tissue between green veins. I'm still learning to grow
lilies myself so I hope someone else can help more with the troubleshooting.

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