Spotted this late, but in any case..
My first instinct would be to get a hole in the lid and an airlock. Even without the grommet, maybe insure seal with tape or I use Glad Press Seal, anything to keep ambient air out. If really blowing off then blow off tube in said hole. Would not want to contaminate entire batch over lack of airlock. Lack of drill to crate hole? Pointed object (knife) ream out hole to appropriate size. Regardless, lid should not be on "loosely". IMHO