There is a difference in flow of GPH vs Flow in current. You can still have large GPH flow with lower current by changing diameter. Still even for lazy catfish, and Id think depending on what catfish you have, they are all heavy waste producers. So the higher turnover rate of 10 times an hour is still better for them and much healthier for them as well.
Chizzle is correct though that the flow rate your mentioning for each of the pumps you mention is the zero head pressure rating. Roughly with your head height of about 3ft your Rio is only putting out 450-500gph an hour max. The Eco 2300 is rated at 2300 liters NOT gallons as per the manufacture specifation and this would be at zero head height. ------ 2300 litres Per hour = 507 GPH. So by the time you get the 3ft head height your only pushing around 200gph.
TO the OP I cant say enough good things about the Laguna pumps. VERY quiet, VERY efficent in electricity. Draws less. VERY reliable. They have a very high output you can fine ture with your system. For 180 gallons Id recommend exactly what Chizzle said. You should end up with around 10x turn over. If your looking to get a second pump as one for backup in case of a failure. Then get a second laguna to match. The other thing is Laguna pumps are reasonably priced. Im not a rep or anything for them Just can tell you of my own personal and recent experinces. This is coming from someone thats used Several other brands out there for years.