Two Gray Tanks

We too have two gray tanks but it actually works for us. We fill both about the same, but think that's the case for us because we are conservative for both. We take "Navy" showers, collecting the water in a bucket from the showerhead before it warms up and use that collected water in the toilet. For the kitchen sink, we use one dish pan of soapy water a day; wiping plates clean before washing or using paper plates. We use biodegradable dish soap so if the tank gets close to full, we will empty that water into a separate bucket and use it to put our campfire out. I've heard of people connecting the two but for us it's not a big issue.