I installed one on the return of the 210 I am almost finished with. If you can install it on a closed loop you wont have to worry about any siphoning problems. When I did a power failure test it siphoned back down to the sump so make sure you have a big enough sump to handle the water or place the outputs at the very top of the tank to minimize that amount of water siphoned. I really like it though! said:An anti-siphon hole just below the water line will alieveiate this problem as well...