if you want to lower the pH of your soil, put Sulphuric acid or soil sulfur

I agree with John - I’ve heard to use 1 tablespoon of vinegar per gallon of water. I would wait for additional comments to be sure :)

Where did you read such rubbish? ? Far far too much acid. Its likely your seedling is dead. Then again you could get lucky and it comes back. Time will tell. Flush with plain water immediately.

I add 1 tbsp. vinegar per gallon to my feed water because my irrigation water is 9.2 to 9.4 pH.

EC, I know you are trying your best to take good care of that tree. I wonder how accurate is your determination of an alkaline soil. I suspect it was not accurate i.e., the soil probably did not require acidification.

Now that you have added acid to the roots of your tree, the next best step, as Johnmerr suggests, is to rinse out the acid with plenty of water. Pour at least two times the pot volume of water through the soil.

Thank you for all the comments! I flushed with water and a few hours now it looks like the plant is perking back up. Hopefully I salvaged it...time will tell. If the pH isn't the problem any ideas why the leaves are rippling and yellowing like in the picture?

The leaves look fine to me. New shoots are normally a light green but darken up as they grow..

I don't see anything wrong with the tree. Don't love the tree too death. Citrus leaves green up with maturity.