You could simplify that a touch by omitting the timer and just use one of these to drive an air stone/bubbler…
Run this quiet, rechargeable USB air pump from a wall outlet or without power for 8 hours. Perfect for power outages or portable transportation of fish.
www.aquariumcoop.com
Having too many aquariums running to count, your fish want oxygen exchange which happens when the surface is agitated. And these are USB rechargeable.
Or look into any of the bait saver bubblers for 5Gal buckets as they do the same thing.