hi i've had 2 60g tanks one glass and one acrylic both for about the same amount of time...i've been sustaining the water temperature for the longest time and now i have a problem with my acrylic tank...the only new thing i've added to my tank is a Fluval FX5 with my old hanging filter along side to help cycle my new filter...since then my water temperature has been on the rise and i've already removed my heater...any suggestions on why its doing this??is it because of my new filter???i've tried taking out about 25% of the water and replacing it with cold water only and its gone down from 83 F to about 81 F...has anyone encountered a similar problem???i could use any suggestions at this point...my other 60 has the same hanging filter with no heater and is sustaining water temp of 78 F...i'm about to put 5 new guinea datnoids in the tank that is overheating, so my real question is can they be kept in this type of water temp without any problems???hence if this degree of heat doesn't pose a problem in raising these fish i have no problem at all but i am concerned...thank you for your time i will appreciate any input from anybody who's delt with this type of problem...