I actually have 3 of these on one tank for the last 7-8 months and they work really well. Yes an XP4 and 2 XP3 sounds excessive on a 115 gallon but I have the tank pretty well stocked but these filters keep this tank crystal clear with 2 units of Chemipure as well. The only thing I would not rely on is Rena states their XP4 can handle a tank of up to 265 gallons. Always better to over-filter....than under filter. They are very easy to prime and maintain as well.

