DIY trace solutions - How dilute is too dilute? When should I remake the solutions?

[StubbyAcro]

Hello @Randy Holmes-Farley. You mentioned in a few threads that the less concentrated a solution is, the less stable it is due to air oxidation. I understand that the rate of air oxidation is different for different elements but I don't know how long will my DIY trace solutions last in semi-airtight dosing containers.

Can you give me a recommendation of when I should remake my DIY trace solutions?

Right now, I'm dosing:

- Iron: Mixed at 2000mg/L of iron
- Potassium Iodide: Mixed at 764mg/L of iodine
- Manganese sulphate: Mixed at 320mg/L of manganese

 

[DanyL]

I don't make my own traces, but I am diluting those I buy for better accuracy and safety when dosing.

Maybe instead of being concerned about it you can make highly concentrated solutions, and once every 1 to 3 weeks make diluted solutions from it to fill the containers.

 

[StubbyAcro]

My tank is only 60 gallon and I only dose small amount to the tank everyday. I make 100ml solutions of each trace element per mixing, which is about once every month.

 

[DanyL]

Might want to wait for Randy's answer just to be sure, but if that's the case, I don't think you'll have a problem.

 

[Randy Holmes-Farley]

What iron ingredient did you use to make that solution?

If it is not a chelated iron, then precipitation of iron oxide is an indication of an issue.

 

[StubbyAcro]

Iron Fumarate 200mg. I put one tablet in 100ml of RODI water. Fergon tablet is hard to come by in my area.

 

[StubbyAcro]

For manganese, I put 0.1g of Manganese sulphate in 100ml of RODI water. Same procedure when making iodide solution with Potassium Iodide.