[APD] Re: Fe and PO4

[Thomas Barr <tcbiii at earthlink_net>]

>> In particular the PO4+Fe reaction is quite quick, 
forming very insoluable salts.  Also liquid stock solutions can start 
growing bacteria, nitrate solutions in particular, so I would add the 
following general advice to what you have (I know you do this but I 
haven't seen it written down too clearly):>>

Yep, we add Fe to water to remove PO4 sand preciptiate it out of the water column.
Then it ends up in the sediment and is slowly reduced back into soublke forms.
Not really a long term solution:)

>>1. Try to add everything dry if possible, and allow everything to mix 
well in the tank before adding additional components.  Try and keep the 
phosphate as far away from other chemicals as possilbe in terms of 
dosing time, especially iron based trace.>>

Yep.

>>2. If you must make a stock solution, use distilled water, if its a 
nitrate solution a few drops of HCl will keep bugs from forming, maybe 
even a commerical biocide like Proxel would be appropriate.  Phosphate 
solutions should have a low enough pH to be okay if added to 
distilled/RO water directly (these are hard to measure dry).>>

Yep.

>>Makes we wonder if the huge uptake rates people report with PO4 (1.0ppm 
to 0 in one day, etc) isn't just a reaction with all the trace/ferts 
we're dumping in.  If you want to see this stuff in action, add a little 
  PO4 solution to some Flourish.>>

I think that might happen, but how much Fe vs PO4 is added?
A lot more PO4.

Where does this FePO4 go?
To the substrate and eventually ends up reduced or vacuumed out, or plant biomass, reduced back into Fe/PO4 by anaerobic conditions. 

Try this dosing of PO4 with DTPH or ETDA Fe also and see what happens.

Regards, 
Tom Barr

>>Jeff Ludwig
>>Elkton, MD
_______________________________________________
Aquatic-Plants mailing list
Aquatic-Plants at actwin_com
http://www.actwin.com/mailman/listinfo/aquatic-plants