Hi and thanks for your answer.

Ok so for 170 liters, if we follow seachem recommendations for **moderate light aquariums**, we add per week :

0.1ppm of iron (3.5*2=7mL of flourish) + 1.5ppm (4.25*6=25.5mL of Flourish Iron) -->**1.6ppm** of Iron each week.

Then if we look at EI recommendations for** high light aquariums** :

3*1/8 tsp of CSM+B per week which represents **0.15ppm** of Iron each week (thanks to the fertilator again)

--> So seachem recommends to add 10x the amount of Iron that recommends EI (which the aim's to dose a lot (too much) nutriments !).

All I want is to understand why such a difference.. (maybe the fertilator is simply wrong ?) It's really weird...

I just double checked the numbers and our numbers basically agree. They are below.

It seems that Seachem recommends quite a bit more Fe than EI. I don't know why.

There are some problems with the fertilator and Seachem's products. The fertilator says that there is iron in practically all of Seachem's line of ferts (unless it's been fixed), but that doesn't make any difference here. All of our products here contain Fe.

I don't think that the Fe calculation of CSM+B using the fertfriend is a problem. After I calculated the weekly EI dosing for 3/8 tsp or 30 mL of Trace I found that all the ppm's of Fe from the three products are basically very close to each other. That's below too.

I use the fertfriend calculator sometimes:

http://www.fishfriend.com/fertfriend.html
I plugged in 170 liters into my Seachem calculator and you dose:

4.5 mL of F. Iron 6x per week and 3.7 mL Flourish 2x per week

Then according to the fertfriend calculator:

4.5 mL F. Iron = 0.2647 ppm of Fe per dose

3.7 mL Flourish = 0.0696 ppm of Fe per dose

Then (6 x 0.2647) + (2 x 0.0696) = 1.7274 ppm of Fe per week - This agrees with what you are saying.

Then using EI for a 170 liter aquarium = 1/8 tsp of CSM+B or 10 mL of Trace 3x weekly

1/8 tsp = 0.12 ppm of Fe per dose or 0.36 ppm of Fe per week from the fertilator

10 mL of TMG = 0.0411 ppm of Fe per dose or 0.1233 ppm of Fe per week from the fertfriend

10 mL of Flourish = 0.1882 ppm of Fe per dose or 0.5646 ppm of Fe per week from the fertfriend

To make the above paragraph easier to read, I'll list each product's ppm of Fe per week. We can see that they are very close to each other:

CSM+B = 0.36 ppm of Fe per week

TMG = 0.1233 ppm of Fe per week

Flourish = 0.5646 ppm of Fe per week

Again, I don't know why Seachem recommends more Fe than EI. This is a question for Seachem's tech representatives to answer.

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