Glass tank. Sump tank 175 gallon tank I know it sounds small but from what I've read it's more about shape and layout then gallons. I'm picking up a pump that does 500 gallons per hour.
Welcome! Glad you're enjoying the site. We have all benefited from it in one way or another. Rays need a lot of filtration. Try and target 10 turn overs per hour for rays. 100 gallon tank = 1000 GPH. There are many factors that go into it but it's a good general way to approach it.
One of the reasons for the large tanks is stable water. The fewer the gallons, the lesser or at minimum the more fluctuations in water parameters as well as more turn over needed. The more gallons in total volume of the system, the more the ammonia and byproducts of the nitrification cycle are diluted. Rays do need a large footprint but the additional volumes in most cases are also very helpful from a dilution / stability standpoint. Ammonia spikes after feedings are much harder to control under the 300 gallon range.
Think of it like this:
(same ray)
X1 ray in a 200 gallon
X1 ray in a 300 gallon = 33% improvement
X1 ray in a 400 gallon = 50% improvement
Etc..
Then there is the addiction side. You may (most of us did/do) want more rays. Just a few thoughts to mull over. I'm a setup junky and happy to chat filtration so don't be afraid to shoot me a message if I can help
