Rats and Compost
I have two compost piles. The first one is a layer of seaweed, layer of old dirt, layer of horse manure, layer of dirt and then repeat until desired size.
My second one is in a large rubbermaid tub with 1/4 inch holes drilled in the bottom (for drainage and earthworms) and all sides (not the top). I layer my kitchen scraps and old dirt until full and spray with water until damp and then turn once a week or more.
I had to separate the kitchen scraps from the open pile because of an invasion of rats. They soon disappeared when their food source was not available.
I have great compost every spring.
Before I had access to free horse manure I used only seaweed that I collected each fall after a storm. My garden is a no dig organic garden and produces great crops.
Some More Ideas for Rat Problems
Your solution for rat problems in the compost is an excellent one. Separating food waste from the regular compost so you can manage it more carefully is a good way to go. This will also work well for dealing with mice and racoons. You do have to keep watch and make sure those rats don't manage to chew through the plastic container. Keep it Moist
I have never had rats in my compost but I have had mice. I live in a dry climate and it can be tough to keep the compost moist. Mice will move in to a nice dry compost, after all it has everything they need. Watering your compost to make sure it is moist enough will help discourage rodents from making your compost their home.Bury Food Scraps
If problems persist you may want to try burying your food scraps in the garden. Some people dig a trench about a foot deep and over the course of time fill it with food scraps covering it with soil as they go.Bokashi Bokashi Composting
is a method to try if you are having serious issues. The rodents don't like the fermented food waste and so avoid it. Plus you are burying it in the ground during the second phase so again the food waste is out of reach of rodent pests.Hardware Mesh
Sometimes rats and other rodents will chew through plastic to get at the compost goodies. The recommendation is to encase your compost bin in hardware wire. It has to be more that window screening as they will easily chew through that too.
Thanks for your story. I envy the fact you have so much seaweed.