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.

Regards,
Tom Barr