Overdosing

Hello everyone :0

I recently won part of a battle with cyanobacteria by dosing nitrates (salt
petre). The cyano slowly over a period of days began to recede, a few tufts
of algae have appeared on leaves since then but nothing serious. What I need
to know is when you are dosing ferts how long do you wait to see a response
in the plants. For instance, if i suspected an iron deficiency and dosed
some ferts to rectify when would I start to see an improvement in the
plants?

Also, my Valisneria is doing well, growing nice and green and sending off
runners but a few of the leaves at their tips seem to be red!!! Any ideas
what this may be? Its not an algae, it seems to appear on another plant that
has ok green growth but then in the middle of the green theres a red rusty
patch! Any ideas?

I am dosing ferts (kent), Nitrates are between 5-10ppm, CO2, pottassium
chloride, lights are 2 15 watt bulbs over a ten gallon tank.

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Kind Regards
Cameron McNeill
RS&E Graphics Dept.