When DEFOAMER products are incorporated into a fluid concentrate; the pH value of said concentrate should be kept with the range of 6-11 to secure good, long-time stability. Use of DEFOAMERs as tank-side additive to diluted fluids is a very common application, and you can apply DEFOAMERs outside the 6-11 range. You will need to test the borderline in your system by practical testing.