Plantex CSM+B Plus Extra Iron vs. plain Plantex CSM+B.

In my opinion, I would just go with the CSM+B without the extra iron.

Flourite is a porous fracted clay which is naturally mined and is rich in iron; primarily ferric.

I not familiar with any reasons why you would want to supplement addition iron into the water column, unless you are keeping a fast growing non-rooted species which would benefit from such...?

Anyone else have some input on this?

Cheers!
Raithan O. Ellis

Obviously there is a demand for iron products, otherwise Greg wouldn't have concocted such a formula. I believe the extra iron users are those with red plants. If you had a majority of red stem/bunch plants, it may be something to consider.
As Raithan stated, rooted plants can get their iron from the Flourite.
Do you need the 10% iron formulation vs. the 7%? Maybe, if you have the aforementioned plants. Will it do any harm...doubtful.
Since you're paying for it anyway, I'd go with the 10%. You can always cut back on the dosage (and save some $) as opposed to adding extra to make up for the lower Fe.
Hard water is a result of higher Mg and Ca, not Fe, but most likely contains many other elements (including Fe). Without doing an analysis, it's hard to say what is in your water (a report from the local water authority would help) but it probably has many of the elements your plants need.

HTH

Will extra iron harm your fish? No
Will extra iron result in algae? No
Will extra iron help your plants? Maybe, maybe not
Will not enough iron harm them? Yes
Does the +iron formulation cost more? No
How long will the iron in Fluorite be a viable source before the substrate is depleted or the iron oxidized? Months to a year.

All things considered, I'd go (and did) with the extra iron formulation.