Heaters Acrylic Sump Safe? w/pics

[JWGarber]

Setting up a 125 and have some questions.

I've always put the heaters in the DT but honestly I hate it.

I was told by the manufacturer of the sump not to put my heater in there because it can melt the bottom.

I've set them on egg crate and secured their mounts to another piece of egg crate to raise them further from the bottom. I am using a 300w aqueon pro glass and a 250w aqueon pro with plastic casing as a backup.

They are not touching the bottom or sides anywhere. So to me this should be safe.

Any thoughts or input here? See photos.