It is FePO4.nH2O, so one Fe+++ to one PO4---.What ratio does iron and phosphate bind at?
That is pretty much it, as soon as the Fe+++ ions become available they will form new (mainly insoluble) compounds, if they aren't taken up by a plant. You can keep the iron ions in solution in acidic conditions, but as you approach pH7 (or have a lot of PO4--- ions in solution) insoluble compounds will form.What is to stop iron that is bound to EDTA immediately binding with excess po4 once the edta complex is broken?
No, it is just going to precipitate out of solution. Because iron is reactive, and most of its <"compounds are insoluble">, it is always going to be difficult to keep in solution.Do you think that dosing FeSo4 is worthwhile in EI situations where po4 is abundant?
This is how "phosphate strippers" in waste water treatment etc work. This is from <"Wastewater treatment: Tackling phosphate removal">What if the other way round? Too much iron depleting lower amounts of po4 due to precipitation?
cheers Darrel....To reduce phosphate additions in the discharge to water courses from sewage treatment works, the sewage is treated with iron salts, which are converted to insoluble ferric phosphate; the phosphate is removed by the DynaSand® vertical sand filters, settled in primary settlement tanks, further treated and used on farmland......
Things are slightly different in the substrate, where iron may be come available in the zones of fluctuating REDOX that occur around plant roots (the rhizosphere) and near to the substrate surface.It’s probably better to keep phosphates in solution and iron in the substrate then ideally.
It is down to the solubility. There is a useful <"solubility chart on Wikipedia">.Lastly if there are more reactive ions than Fe (K+, Mg) why do we only talk about FePo4 and Capo4?
Quite likely, the <"plant available phosphorus"> will be a small fraction of the total phosphorus reservoir.Could this be one of the reasons that people report better growth rates when adding large amounts of PO4, the fact that the likelihood of plant uptake is increased increased opposed to the actual concentration added?
It is really difficult to tell, as you probably gathered from this thread nutrient issues aren't always a simple case of how much you've added.I have a lot of GSA on my glass which is said to be an indication of low PO4 however, even after halving my PAR the GSA still forms. Perhaps i have a po4 issue here?
My suspicion would be that you should have plenty of everything, a conductivity reading would be interesting.In my soil tank, things only really began to take off when (along with some other changes) i stoopped adding iron, calcium and magnesium and left these things to the soil. However i carried on with EI values of NPK. I had lots of red clay in a deep soil substrates and as i understand it the John innes no3 soil is nicely limed and most likely contained plenty of Mg and Ca.
Trying to micromanage nutrients is not the best strategy. All the hand wringing about what precipitates is simply wasted energy.On the flip side, if i increase PO4 dosing I don't want to increase the probability of iron precipitation either. I am trying to think of ways to maximise the addition of my fertilisers to avoid precipitation based deficiencies.
Yes, you are being pedantic. It will be the death of you. Death by pedantic is the second most common occurrence in The Matrix. The most common, of course, is death by test kit.I am currently dosing my Magnesium with the NPK. If we are talking about separating Phosphates and Iron would there be any value in putting the magnesium in to the micro mix to prevent any possible Mg+Po4 precipitation or am i being too pedantic again?
OK, well, that's a good start. I'm never sure why folks feel that dosing is a matter of strictness. You're only dosing 5 of the 7 days a week. Surely you visit the tank 5 times a week or more? How often do you feed the fish? Is this considered strictness or fun? If it helps the psychology maybe dose at the same time that you feed.I have not been strict enough with keeping to EI in terms of dosing so I am starting as of today. I did a 75% water change last night and this morning i dosed my EI macro mix. Tomorrow will be micros etc.