Carbide does not rust so tap water is good/great
Home made coolant is washing soda and water. This is for rust avoidance only as water alone is good. and good because you can dump it with no fear of pollution. Dump on the grass is OK. (n0T the kind you smoke)
Pink liquid soap(Calgon best) and water is OK/good, about as bad as washing machine soap going down the drain.
Any store bought bio / coolant
QT HotRolled:[ I would not use an oil based coolant.] agree, it gets stinky and not bio friendly.
Good to shut the coolant before turning off the wheel so coolant is less likely to get into any bearings.
* How washing soda (not baking soda) works is that it leaves a fine powder on the surface so the water dries with not rusting, but the metal is clean so an oil rag wipe is a good follow-up. Washing soda coolant on a hot surface will leave a paint like coating that is not easy to remove.
A broken chunk of green wheel or a dressing stick will lower the wheel bone to let the diamonds stick out for better grinding and less wheel wear, Mount wheels with less than .002 face runout with using copy paper shimming is OK, this assures that at the end of wheel use the wheel will not run out of diamonds on one side. Watch for a hole or indent hollow at the wheel face and then try to work that out with grinding on the high place to keep the wheel as flat6 as possible. The same is for right or x left of wheel face to not get high get high -> try to keep the flat 90* to travel.
A Box shield can be fabed up to keep almost all coolant from going about the shop. not a bad idea to wear a decent mask for such grinding.... of plexiglass allows good light to show in.