I've had great success with EVOH wine bladders. Mix up the entire 5 liter batch of replenisher and store in astra pouch wine bladders. I even mix straight into the bladder so one less thing I have to clean. So far I've had a batch stored for 6 months with no discernable degradation on my control strips. Probably could've gone longer, but I used up the batch. I don't shoot much b&w so I've had a 5 liter batch of xtol mixed since January 2022 that's still kicking store in the same manner. It's a really good solution if you're doing one shot development, but also good for mixing up bigger batches and then making your way through it 1 liter of working solution at a time.
The big advantage is you're never reintroducing air into the system like you would every time you open and close a bottle and the nozzles are precise enough to dispense the exact amount you need.