If I have 6 or 8 lobster tails or a 5lb roast , what are the displacement volume limits? 2 chicken breasts vs 6 what are the limits of weight vs volume of water?

Firstly, when talking sous vide processing one needs to stop thinking in terms of weight and start thinking in terms of thickness. Cooking is all about heat penetration and how long it will take for the heat from your cooking source to penetrate to the core of your item. Thickness is what impacts this. It always really has, but weight was just more convenient to quote because foodstuffs are purchased by weight.

Now… You’re talking weight versus water displacement… well, that’s a matter of volume.

Or perhaps you are trying to ask how much you can cook with one Anova without putting a strain on the device? The 900 watt WiFi model gives a recommendation of around 24 litres of water. However, these are not absolutes either. The main strain on the Anova is in the initial heating phase, so if you use water that is already near the desired temperature there is less load on the unit.