how long to keep star-san in plastic carboy

[reelseasick]

I don't know why I sanitized by carboys tonight for tomorrow, but I did. Is it ok to keep star san left over foam in better bottle for 18 hours?

 

[joelr]

It shouldnt hurt. But I'd resanitize just before you decide to put your wort in it. I assume your using it as a primary fermenter.

 

[Zen_Brew]

Neither Starsan or the foam will harm the carboys. You can keep it in there indefintely with no ill effects. The foam is sanitizing as well and is what helps the sanitizer get in the nooks and crannies.