any additives i can add for better softie growth?

[Anemone]

as above.

iodine? iodide?

[moxa]

Hi,

I believe you aware additive are not main source of food.

Most common addititives would be iodine,Magnesium and Strontium and even Trace Element.

Is best you search for your type of sofies and confirm the requirement which will include the water flow and lighting.

http://www.liveaquaria.com might be a good place to start

Cheers

Moxa