Sooooo again my PH has spiked this time to it's lowest point (right around 4)

WTF!

Also my roots are sitting in the water because I'm using the drip system in 5 gallon buckets

I'm changing the water but in the mean time should I do anything with the roots to get the low PH'd water off the roots?

And Another question... I heard somethig aboyut spraying seltzer water/club soda/tonic water on the plants and roots does wonders?? True??