Mead foaming out of the airlock: blow-off tube time?

Headspace is the whole cause and fruit is the aggravating factor. A melomel throws a serious cap and needs far more room than a plain mead, so next time ferment in a bigger vessel than the batch needs and transfer to something smaller for aging once it slows.

That also fixes the problem properly rather than managing it, because a blow-off tube on a vessel with no headspace is still going to push fruit into the tube.

Bad for your kitchen, fine for the mead, and switch to the tube now rather than hoping. An airlock that has had foam through it is contaminated and it will keep clogging as long as the krausen is rising.

Sanitised tube from the top of the fermenter into a jar of sanitiser or water, and the foam has somewhere to go. Clean up around the outside, put a tray underneath, and let it get on with it. The active phase usually settles within the first several days.

Move it somewhere cooler too, inside the yeast's range. Warm ferments are more volcanic and taste worse.

One more trigger worth knowing, because it catches people who have done everything else right: adding nutrients or stirring releases a sudden rush of gas. Pour nutrient in all at once on day two and you get an eruption out of a fermenter that had been behaving.

So add slowly, a little at a time, and degas gently rather than stirring with enthusiasm. The mead volcano is usually something the brewer did in the preceding thirty seconds.