The 'white ' vinegar is the one you want to use.

It acidifies your fertilizer solution so that it's not too Alkaline. If your water is Alkaline or above, it will prevent many valuable nutrients from being absorbed by your citrus tree, including Iron and Mg no matter how good the fertilizer is..The leaves will turn yellow, leaf internode will be too long or short, leaves will will be scarce, growth will be slow and eventual decline to the point of death........Many greenhouses, well a few I know in California and all here use commercial product diluted into their fertilizer solution at every watering....Four Winds does, and look at how green their trees are. In fact, they were the ones that gave me this knowledge years ago that I have been compelled to share over the years..

I have been growing Citrus Trees for over 20 years, and I never heard of this until a few years back and was never successful with my trees in all ways until then. For me, vinegar was the key. I am thinking to this day, they may have other acidifying techniques that the public can buy for potted plants that require a lower pH than what most of us can provide through tap water, and maybe other could share what they use.

You can use the same amount per gallon for every tree whether large or small, and for most if not all Tropical plants..

Well, I've used Apple a few times cause initially I was out of white. I read in a thread that either were ok...I guess white is better?? I bought some recently, so can use that one from now on.

Thank you very nice

Distilled/white vinegar are the same thing--they're produced from the fermentation of distilled alcohol. They mainly help with alkaline tap water when used in conjunction with potted media. If your trees are in the ground, elemental sulfur will do a better job of acidifying the soil.

I usually use about 1 tbs per 5 gallons of water when I fertilize, but my water isn't exceedingly alkaline (pH around 8, and remember, pH is a log 10 scale).

-Tom