flourish micro dose for EI - need dosage confirmation, conflicting search results


Junior Poster
Nov 26, 2011
Hi everybody,

This is my first post on this forum, but I've been lurking around for a while now slowly soaking up the massive amount of info! ;)

I posted this same question on TPT, but didn't really get a clear answer so I was hoping that people who were more familiar with EI could chime in and help ease my worries.

I've been dosing plantex CSM+B as micros, but would like to try out flourish comp. a few weeks as a micro just to compare. There is alot of info about CSM+B dosing, but there seems to be lots of conflicting answers for flourish dosing.

According to Wet's EI calculator, it bases the micro dose on iron to 0.5ppm. The tank I am dosing is 29g - so the calc says that I would need to add 17ml of flourish comp 3x a week for my micros. In some of the threads I found during my search, people were recommending 5-6ml dose for a 29 gallon? Wouldn't this not be enough iron or an I completely missing something here or using the calculator wrong...?

Specs of my tank:
29 gal
2x 24 t5ho
pressurized CO2 ~30ppm
EI dosing, 50% wc once a week

very heavily planted with lots of fast stems:
Alternanthera Reineckii
Rotala Roundifolia
Cabomba Pulcherrima
Limnophila Aromatica
Nesaea Crassicaulis

Also, should I be supplimenting iron in addition to normal micro dose to help bring out reds in some of the above plants?

Thanks in advance!
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Lifetime Members
Lifetime Member
Aug 6, 2008
Well Tom said in a thread once that dosing 0.5ppm fe was rather on the high side. Wetts calculator gives you a marker that shows you that EI dosing is between 0.1 and 0.7ppm. Based on your story, not on knowing the actual product, i would start off with half of the recommended dose, e.g. 8-10 and see how your plants react. They need time to adjust to other ferts just as good as they need time to adjust to higher light/co2. P.s. i only dose CSM+B and Ferrous Gluconate for extra iron and have been doing so for 2 years straight.


In an attempt to save you the hassle, don't use Flourish. It's a lot of water with minimal ferts in it. I had to learn the hard way, and once I went to powders I never looked back.


Lifetime Charter Member
Lifetime Member
Jan 5, 2009
Washington, DC
As if "conflicting search results" is a rare thing.

Iron (Fe) is only a proxy for the other trace elements that are included in trace nutrient mixes. I am not sure adding more iron has been proven to increase red coloration in plants.

One concern I have with Flourish is that the source of N in Flourish might include urea. I'm not 100% sure.

If you dose Flourish Comprehensive according to the bottle (say 2-5 mL in your tank) the dosage is very close to those of PMDD and you run a real chance in high tech tanks (pressurized CO2 ~30ppm) of high nutrient needs and limiting nutrients. It's a good god sort of thing.

Adding two full caps (about 10mL) would provide your tank with the very low side of EI (still within the EI model). You might find your plants do well and we are talking about an expensive product so it's win-win. I could suggest at least a 15 mL dose to start the week dropping to 10 on the other two days.

If you didn't read, "The Estimative Index - What is it?" - try reading that.

Math, can be suspect - if you can't go long hand,
go wet's calc.
or wet's calc mobile.
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