Thanks for your kind comments on my video. You can absolutely use water rather than air to artificially incubate your eggs. I've done this many times and it works quite well. The advantage of the air driven tumbler is that you can put many of them in the same system and you won't affect the total incoming flow into the system. If I wanted to incubate 6 separate clutches of eggs appropriately with incoming seawater, you could overwhelm the tank discharge and overflow your tank. With the air driven models, you can have any number of tumblers and you will never impact the flow dynamics of your system. Also, I work for a large public aquarium and flow pressure changes periodically throughout the day and night, so the air method provides the most consistent incubation results. As with many things, there are more than one way to accomplish your desired results. So whatever makes the most sense for you setup, you should use.