This is my first FW Planted tank. Previously however, I spent years as a reefer and a FW fish only tanker.
So, my past experience has been that the tank's (Fresh and marine) summer time temperature rose to approximately 80-82 degrees. Normal water temperature during the winter months is 76 degrees.
In the ten years or so that I have been keeping these tanks, the increase in temperature over the summer has never caused a problem with the inhabitants - fish, inverts, or corals.
The caveat is that this will be my first summer with a FW planted tank so unfortunately I cannot give any advice as of yet.
That said, reefers often purchase chillers to keep water temperatures cool. I've never used one, don't know how much they cost, but if I recall reading about them I think they work really well.
Hope this helps.
*Substrate = 50% Florite sand 50% regular Florite
*Lighting 108W of a 216W T5HO Aquatic Life hood 25" from substrate 8.5 hours daily.
*Amarath Redroot, Waterhyssop, Brazilian Pennywort, Water Wisteria, Jungle Val, Moss Ball, Riccia, Nana, Java Lace, Cryptocoryne, Pigmy Chain Sword.