DWhatley is right with these tips. A skimmer goes a long way towards improving water clarity with ceph tanks even without inking events. I also agree that usually for most small inking events they can be cleaned up with a turkey baster or a careful siphon. The best thing to do if you are concerned about taking water out of the tank, would be to have a sump or reservoir underneath the tank that you can use to top off the tank if you remove some water from it. This way you can be sure that you aren't changing pH and temp and salinity etc.
A note about water changes- generally its good practice to not remove more than about 10% of your system volume in one water change. Also, when you do a water change, the water that you add will need to be slowly added back to the system to ensure you prevent things like wild swings in pH or temperature. If you are more curious about the mechanics of water changes I can go into more detail if you'd like.
A tip about preventing inking events: When you interact with the animal, move slowly. The majority of times I have made an octo ink was because I was moving too quickly inside the tank or I scared the animal by walking by too fast etc. The other time that I've had an octopus ink is when I am moving it from tank to tank. You probably won't be doing this much, but if you ever do have to move your octopus with a net, make sure to support the net from the bottom with your hand as you move the octopus (eg. one hand on the net handle, one hand underneath the net supporting the weight of the octopus). This is because octopuses don't have any internal support structure (like our bones) and they lose the ability to support themselves when they are out of the water. Supporting the animal inside the net is a good way to keep them comfortable when moving the animal from tank to tank.