COOLER TANK TEMPERATURE REQUIRED.

[Ray.M]

I want to run my tank (community discus tank) at a few degrees lower 27-28C because the higher temperature is causing issues with my plants, Corys, ottocinclus & whiptail.
Even with my heater off the tank gets to 30-31C in summer.
Can anyone recommend a practical way to lower the temperature ?
Is a chiller the only way ? If so, can you recommend a brand and size.
My tank is 300L but I am hoping to upgrade to a 650L tank.
Thanks,
Ray

[Nev]

Leave the cover glass off, should drop the temp a bit.

[swampy1972]

Increase the aeration with either (or both) an airstone or more surface agitation with your filter return.
If that isn't sufficient you can also look at using a small cooling fan (EBay search) that are popular with shrimp keepers. They simply blow air across the surface and work by evaporative cooling. The trade off for cooler temps is that you'll have greater evaporation, but they're a far cheaper option than a chiller.
If you have the option, maybe also consider relocating the tank to a cooler part of the house..

[ILLUSN]

replace the lids with small flyscreen ones you can buy the materials to make the frame at bunnings