The way I understand it, so-called "acid-loving" plants are not literally acid-loving but rather very poor absorbers of iron. Since iron is much more available at lower ph, things like blueberry can only survive under those conditions.

So, although I'm not sure to what extent liquid iron actually lowers ph, and this probably depends on the specific product you're using and the copper sulfate amount, it should clear up the problem, since it supplies the iron that the plant is lacking. It clears up chlorosis in potted citrus within days.

Hopefully you mean iron sulfate. Copper is toxic to the soil/organisms. Iron sulfate would be good until you can get the pH right.

Fertilome liquid iron says it has copper sulfate as a trace mineral. SO Im assuming its a minor amount of it.

In a related vein, the horticultural product "copperas" is iron sulfate, even though it sounds like it should be copper, which as mentioned would be very easily toxic.

I think iron sulfate may eventually produce some acidity as the unabsorbed ferrous (reduced) iron oxidizes and hydrolyzes. That is basically (excuse the pun) how horticultural aluminum sulfate produces acidity I believe.

My experience too. The Iron sulfate barely moves the needle on the overall acidity of the soil, but it has a dramatic effect on the plants.

I don't think it dissolves instantly in water, so the water and copperas have a chance to leach into the soil a few inches, making new acid along the way, and releasing nutrients especially iron, for a few centimeters as it does so.

Harvestman likes to say that highly organic soil doesn't have to have a low Ph to grow blueberries. I think its the same interstitial effect, only with organically created acids.