I would like to pipe in here. I ran across this thread searching for something regarding nutrient uptake rates in Co2 injected, high light, EI dosed tanks. I was dosing my six gallon with a higher recommended dose of macros and micros. The reason was because even at dosing 1/4 tsp of K and N and a 1/8 tsp of P three times a week I was getting less than the recommended levels of the fertilizers (I always test before and after a water change). I erroneously decided to bump up my CSM+B to match the other ferts since I assumed that it was being taken up by plants just as fast as the macros. I never even considered for a second that micro
nutrients can build up faster and are used more sparingly than macros. Well, lo and behold my plants, specifically Telanthera reineckii, started to be affected. The leaves elongated and began to twist up and become wavy. When I tried to move them around while doing a water change, the leaves were breaking off from the pressure of the siphon touching them. I'm not talking about breaking at the nodes, either. They broke off mid-leaf. I decided to start measuring my doses through a gram scale again, and after a few weeks my levels must have leveled out because all of my plants recovered.
I did a lot of researching while I was trying to figure out what was causing my plants strange stunted growth. I came across a lot of "deficiency" type articles, but I ruled out those because I was certainly OVERDOSING
my plants. That's when I started to look at the effects of having excess nutrients, one nutrient at a time. Now I would like to say that everyone is different, and every tank is different. I've seen where people dose up to 8ppm of iron in their tanks with no ill effects. Other people, like me hardly dose it at all (I can't tell you what my ppm is because I don't have an Fe kit). However, with that being said, I have found a pretty good thread (an experiment, too) that pointed to excess Fe causing symptoms in plants similar to mine: http://www.aquaticplantcentral.com/f...much-iron.html
. If you don't read it, just know that the guy was performing an experiment with dosing 50ml every other day with fluorish but accidentally did so with Fe and he got symptoms similar to what I had and what was described in this thread within the week.
Further reading led me to this very scientific article of Fe's role in aquatic plants in different water parameters and its chemical properties that determine its availability to plants: http://www.skepticalaquarist.com/ferrous-ferric
. After reading this I can definitely see how some people can get away with dosing more and how some are fine dosing less. It all boils down to a lot of different chemical variables based on our individual tanks.
Lastly, this article comes to mind and I think that Tom Barr makes a very valid point. http://www.barrreport.com/forum/barr...-iron-toxicity
If you read it, you will see that basically, unless someone does an experiment that proves the Fe in CSM+B is for sure causing these problems, its hard to say that the problem is excess Fe without at least a little doubt. My personal hypothesis is that there is little known about the effects of excess nutrient effects on aquatic plants (although there are a plethora of scientific articles on the subject regarding agricultural plants) but that I do believe that Fe is responsible for the stunted growth I had on my red Telanthera.
In any case, I wish that I had more time and tanks. I would love to set up a test where I could create a dosing regimen, have a control, and see what the effects on the plants are with excess nutrients. We all know what the lower threshold of nutrients are for our plants but we don't know the excess, probably because in most cases our plants grow fast due to the environment we cultivate them in, the EI method allows us to over dose in a way that doesn't add up to super high levels (most of the time), and regular water changes also bring these values down.
Anyways, I that's just my 2 cents on the issue. Thanks for a great thread!