11-02-2009, 08:45 PM
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Originally Posted by Jack Middleton
A gram of KH2PO4 every 2 days, will provide approximately 3.9ppm of potassium, In terrestrial plants excess K can and will block active iron transportation, but in the aquarium levels of 3.9ppm simply isn't high enough to restrict the uptake, and their is no scientific evidence to suggest that it will block iron intake, In another post you said that when you dosed high levels of K you noticed that Iron wasn't being up taken by the plants, This will more than likely have been caused by Magnesium, Zinc and Copper, which in excess levels will restrict iron uptake.
Adding a gram every 2 days will need to be followed by a 50% water change at the end of the week.
In Aunt kymmie's situation, it was solely potassium that was overdosed, no other nutrients. And my surmise, which turned out to be correct, came from information I had read on one of the plant forums. I'm honestly not sure which one it was now, belonging to more than 7 forums I find it difficult to keep track. And we are talking low-tech, not high-tech in all this. Mr Barr is correct to point out that his EI system is better applicable to high tech aquaria.