pH UP isn't good for the microorganisms, no. Baking soda isn't that great either, due to sodium.
Liquid lime or plain dolomite lime, oyster shell (calcium carbonate) are all good for rising/stabilizing pH in organics. I think pH down is alright to use, but still might not be necessary. The majority of organic fertilizers are acidic and will lower your pH enough, so between those, lime/oyster shell and the microherd you shouldn't have to worry too much about it.