Yup, then it can circulate 5 gallons. I would recommend checking out this thread: Best Vessels/Containers for Precision Cooking - #30 by jim777 (some of the photos don’t load on it, but there is enough written to understand what vessels they are using)
I personally use a cambro and it works great, but I have heard that people also like to use stock pots and coolers, check out the link though it has lots of good ideas!
If you want to be a full capacity maybe buy something that is around 20 liters (or more to have a little extra space), because 18.9 is the limit in liters and you want enough room to account for displacement and a little wiggle room for placing your steaks in the water.