Yes, drain adapter for the cup routed to a bucket. I have a 2 liter pop bottle inside an IO salt bucket to collect skimmate. The plastic bottle cap has one hole drilled into it to accept the vinyl tube & a few smaller ones to vent any pressure that could build up. The bucket is my secondary fail safe, I've had a few occasions where the skimmer overflowed & the pop bottle was insufficient to hold the fluid, bucket saved my butt. But I also agree with others that leaving a tank totally unattended for weeks is inviting disaster.
Another old industrial look photo featuring my wooden air diffuser driven skimmer. Situated on a little stand attached to the display stand. Don't recall whether it had the drain adapter already or if I added it. The skimmer came with the tank. Here's a photo of it labeled as to various functions including drain.
