I Just Became A Member .. And Already It Has Helped .. I Also Have A Pond, However, It Is In The Center Of A Planter Surrounded By Plants... The Pond Is 6' Round And Cones Down To The Center Where It Is 2.5' Deep ... I Also Have Fish To Big To Bring In .. I Purchased Two Cattle De-icers, Submerg And Floater, Will This Be Enough To Keep My Fish Warm At Approx. 4 Deg. C.