If thermos if dodgy ditch it asap @85 deg that's 13deg over ideal and could fry# @68 deg that's only 4deg below ideal

Research the filter there are pro and cons with them# I like them but mines external low flow and gets cleaned frequentlty# you need to make sure the filters suitable ie silent and the flow is not to fast or sprayed#
If your going non filter prepare for more frequent water changes and monitor water PH amonia