If it was me I'd get a hot tub floating dispenser and put in a few ****s an let it loose.

I'd also pour in the maint dose of poly 60.

I can't tell you how many times we had people post here that a (friend, neighbour, inlaw, work assoc ) was going to add some chlorine, and they came back to a swamp.

I would dose it up high before I left and let the floater do the rest and leave the temporary help out the picture altogether.

I you were going for 3 weeks, that would be different.

As said above, a well set up pool is pretty resiliant.