"So, when my tank shows 1ppm, can I just stop dosing micro or should I continue (I only do a 50% WC every 3 weeks now)"
I may misunderstand this question, jonny_ftm, but for clarity it is important to note that Fe levels in traces are only a proxy for all trace levels. So, let's say your tank uptake Mn from CSM+B -- having Fe available does not mean Mn is available. This is where the regular input crowd will yell "See!"
I like Tom's points about using different chelators of varying strengths as a sort of staggered approach. I will be trying this in a couple weeks (other experiments with EDDHA at a hobbyist level first) but believe barbarossa4122 is now.
I'm sorry I do not check multiple forums and especially this one in some time. Time forces me to be mostly monogamous with aquatic forums. But for those not on APC, here's some things about EDDHA as Sprint 138 copied over:
What we know about EDDHA chelated Fe (Sprint 138, aka "Super Iron")
6.0% EDDHA Chelated Fe. The label looks like this:
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What we know about EDDHA chelated Fe (Sprint 138, aka "Super Iron")
6.0% EDDHA Chelated Fe. The label looks like this:
This image has been resized. Click this bar to view the full image. The original image is sized 800x600.
It is a very dark substance that will stain the water. The left is a large (~1.0ppm into 20 gallons) wet dose and the right the trial/experiment sample of dry. I am sorry for the cellphone pics. I'll update these images this weekend if you'd like.
Weight trials (10) for 1 leveled teaspoon (5mL) show a density of 2.42 grams per 5mL.
Trials (scale accurate to 10mg)
2.42g
2.42g
2.43g
2.42g
2.42g
2.42g
2.42g
2.42g
2.43g
2.42g
So,
about 1/8tsp adds 0.2ppm Fe into 25 gallons.
about 1/16tsp adds 0.1ppm Fe into 25 gallons.
Here is a calculator I built that does Plantex CSM+B, Miller, 10% DTPA and 6% EDDHA Fe
http://wet.biggiantnerds.com/fe_calc.pl
At 0.2ppm Fe it will color the water pink. Certainly gets your plants redder looking ... an optimist might call it a free 9325K effect This video is currently being processed by YouTube but has a test of 0.2 ppm Fe into my tank. It still retained a pink tint ~12 hours later.
http://go.aquaticplantcentral.com/?id=673X1261&url=http://www.youtube.com/watch?v=ZCTu8ClcMKc
I am going to continue to experiment with this chelator. However, the side effects probably mean we have to use it at a low concentration, which may mean it can only be a supplement to other sources of Iron. For example, Tropica uses some percentage of DTPA and HEEDTA in their solutions, and Tropica Master Grow is a pinkish purple that does not noticeably tint the water column after 5 minutes of dosing. I can continue updating in this thread if there is interest else I'm sure I'll post about it in whatever threads it is relevant in
... and here's 0.02ppm dosed into my tank (forgive the mess) and 10mg into a cup with exact light (nfrank's request for a photosensitivity test):
and the same 3 days later: