If you only need to drop a couple degrees, look into fans. I ran two clip on fans on a ~100 gallon system in a hot garage (peaking at 90+ degrees) last summer and was able to keep it under 84 degrees no problem. Helps if you have an Apex to control the fans.
Try putting it somewhere more permanent. I’ve seen euphyllia look shrunk up and crappy like that just because once they start to open up the flow will make it wiggle and it stay small. Wedge it in some of your live rock and see if that helps.
Ha, I was thinking protein skimmer.
Check with Ferguson, they might have some cut offs. Or, your local PW might help you out if they have some scrap in their yard. I’ll keep an eye out at work too.
If you’re buying sps frags from a shop that has them in a frag tank with t5s three feet off the water and you’re throwing them in your tank right under leds that are pinging 350 at the coral, that’s gonna be a problem. I think that might be more of your problem than a rusty clamp. Just a thought.
Why are your nitrates so high? Do you have a crazy high fish loading? Is your testing accurate?
I would strongly advise against carbon dosing on a tank that new and small in volume, been there done that.
Do you have a build thread, can you post a picture of your tank and sump?