Depending on the complexity of the setup I would either:

Build a very small and basic system that you can use for flush consisting of a small res and a basic pump. Focus must still be kept on circulation and oxygenation, and at the least use distilled. You can build a system like this for very cheap, you would be surprised.

Put them in bins, and manually administer distilled or RO water, depending on setup this could be laborious.

Flushing makes a noticable difference in the taste, texture, smoothness, toxicity, combustion, and body of the dried medicine.
imp: