PO4 and FE


Lifetime Charter Member
Lifetime Member
Oct 17, 2006
Phoenix, AZ
I am trying to understand the logic to dosing Macros and Micros on separate days. From what I have gathered we are really trying to avoid dosing Fe and PO4 together, but...

what is the difference between dosing PO4 and Fe say 3 minutes apart, as opposed to dosing PO4 today and then Fe tomorrow where my ambient PO4 is say 2ppm? It seems like you have the same recipe either way...

Or, is it all about the dilution into the water column? Am I just trying to keep the little cloud of PO4 from hitting the little cloud of Fe before they are diluted more completely into the tank environment?


Jan 24, 2005
Cologne, Germany
I've been dosing the stuff at the same time and also one day apart just for testing. There is no difference really. Dose PO4 and Fe where you have good current such that it will be carried away immediately. That's all.

Don't mix PO4 and Fe in one bottle though. It will precipitate.

What's going to happen if a new Fe dose hits residual PO4 remaines for the more chemical challenged.

Best regards,

Tom Barr

Staff member
Jan 23, 2005
I have never noticed any issues using PO4 and TMG.

Quite a few have noted the flourish and PO4 white cloudiness.

Dose is defined as: exposure (time, area of contact) X concentration.

Note: you can have high concentration and low exposure or high exposure and low dose.

We add the Fe and it comes into contact with the plants, they use it.
If we add PO4 ands Fe, we will get some precipitation and less of the Fe will make it to the plants.

That's all, just do not mix, as mentioned, the Fe and PO4 into a dosing bottle etc.
TMG has a stronger chelator and is thus less of an issue with it precipitating.

So there's higher concentration, and longer time of exposure, but it's less available to the plants.

That's the trade off and it seems to work very well vs Flourish, especially in harder water.

Tom Barr