[charlie b]

For a percentage with a refractometer i usually mix it at 7%,for volume measurements varies for different coolants but for most its around 400ml to 25L it should look opaque milky white (with a blueish tinge when spread thinly on a surface, try pouring it on a flat dark surface to form a shallow puddle and you will see what i mean. pH also varies for different coolants but if you mix it at the right spec it should be fine if you have not got universal indicator papers for this.