[pablos]

I’m currently using Seachem Iron and dosing 0.25ppm Fe every other day.
Regardless of that dosing one said that there is iron definitely in my plants

my pH is high. 24h aged water taken from a tank is 7.7. After co2 dosing - before light turn on it goes down to 6.7.

I consider to switch gluconate to more effectively source of iron. Should I target a mix of EDDHA & DTPA?

In place where I leave there is not a big selection of available Fe fertilizer. Would those work?
Is it some ‘fish safe‘ indicator?

ultraferro - Tradecorp | Australia

The premier solution to prevent and correct Iron chlorosis TECHNICAL SPECIFICATIONS (w/w)

tradecorpaustralia.com.au

Iron for for Organic Aquaponics Soluble - 10% - 16oz (196 gallons) (16oz)

For use on turf, nurseries, landscape plants, gardens and vegetables. Derived from Technical Sodium ferric diethylenetriamine pentaacetate. The recommended dosage is 3-5mg/L or .04 - .07oz/100gallons Highly Soluble and Suitable for all hydroponics, aquaponics, soil, and foliar applications...

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[Betta Splendid]

You should try DTPA first. I hear EDDHA will stain your water red.
Gluc doesn't work in my water so I'm using DTPA. I don't know if those you listed are aquarium safe. Maybe you can try dry fertilizers that other members here use.
You said you don't have a big selection of iron where you live. If your pet shops there carry API products (every pet shop here does), look for Leaf Zone. It's DTPA iron and Potassium. Just check the back of the bottle first to make sure you got the new ones with DTPA. They used to use EDTA but I'm not sure when they switched.

 

[pablos]

I tried EDDHA in one tank. They said form 0.2ppm it might tint your water. In my case with 0.1ppm it’s already bloody.

I might try with DTPA as you suggested either with dry powder or API product. By any chance you know type of iron do they have inCSM+B? Would it be effective in my pH?

 

[Betta Splendid]

I believe CSM+B is EDTA. It's most effective at PH 4-6. However, many people don't seem to have problems dosing EDTA with higher PH. Just keep in mind, if you go with the API, there is also potassium in there. Their weekly dose adds 0.13 iron and 3.29ppm potassium.
That's too bad about EDDHA tinting your water, especially at 0.1. I had been thinking about trying it out.

 

[pablos]

Actually I have way too much potassium, so adding more from API leaf product might do things even worse.

regarding colors you might take a look on that blog

Iron Chelate Interference: The downside of Fe-EDDHA and FE-HBED - Scott's Pride Farm

This is part of a series on Aquaponic Water Testing In an Aquaponic system, we have to rely on some sort of chelate to keep iron available to our plants. Without a chelator, iron is only stable at pH levels below 4. Fe-EDTA is the most common form of chelated iron found, but EDTA is … Continue...

scottspridefarm.com

in my case similarly to someon’s comments it didn’t reflect my tinting. mine 0.1ppm looked like 1ppm of an author’s photo.

Anyway my Seachem Iron bottle is almost empty, so I will switch Seachem Iron + Seachem Trace to simple CSM+B. Hopefully EDTA would be better than gluconate.