Re: Beware to much iron

This post illustrates two important points. First, micronutrients have an 
extremely small range of 'sufficiency' ... too little results in 
deficiency symptoms and too much results in toxicity. Any micronutrient 
mixture should, therefore, be added cautiously. Secondly, test kits in 
general are just not sensitive or accurate enough to pick up small 
changes in nutrient levels (no matter what the kit you are using). If you 
want to ensure continued healthy growth then look to your plants! They 
will tell you if something is wrong in your tank ... I know this is more 
dificult than the comfort of a color change in a test tube but in reality 
it is the only method that will work consistently (its also a lot