AquaChek Blue Biguanide 3-in-1 Tests for: Biguanide, Total Alkalinity, pH Blue 3-in-1 is ideal for customers who use biguanide as a sanitizer in their pool or spa. Compatible with a range of Baquacil™ products. FIND AN AquaChek RETAILER Product Insert Product Demos FAQ Product Information Recommended Products Product Information Biguanide: 0-50 ppm Total Alkalinity: 0-240 ppm pH: 6.2-8.4 Blister card. Biguanide, pH and Total Alkalinity. Recommended Products AquaChekSelect Kit AquaChekYellow