The foam is most likely algae that has a lot of gasses from decay that lifetd the growth from the bottom.
I always suggest 2-3 times the suggested per-acre lime recommendations for several reasons. Mainly because the rate is to reach a minimum often lower than desired PH, also usually for a single year growing season at said PH. Also because the lime buffers normal PH swings, adds needed calcium for growth, reduces clay turbidity and application frequency. and just generally makes fish healthier and less srtessed.
