That may be a Matt-Son injector. You can replace it with a Clack or another brand but I do not like air injection, they usually don't work all that well and especially for iron.
You say you have more ferric iron than ferrous, IMO you shouldn't be using air in any form because of that. Rust builds up in the injector and coats the inside of the pipe from it to the vent tank, and if the vent or retention tank doesn't have a bottom drain, rust builds up in it and eventually gets out into the turbidity filter and ruins the mineral.
Air in any form for H2S only is good if you can get enough air but I've never sold air injection and I quit selling air pumps a number of years ago because adding air to water can cause water quality problems and bacteria growth. Since then I use an inline erosion pellet chlorinator system including a bottom drain mixing tank equivalent to a 120 gallon retention tank. It oxidizes everything and kills all types of bacteria etc. There's no moving parts because it is non mechanical. And then the turbidity filter is a backwashed special carbon but...
For your small amount of iron, I think air injection or an air pump is overkill.
Do you have a turbidity filter? If so it isn't working or you wouldn't have the 'sediment' you mention. And the vent tank is probably too small or loaded up with rust.
How about a picture of everything.