haha if i quit every time i lose a coral or a fish i'd be out of the hobby on the second week, most other reefers will agree . That being said , if you're in this hobby you have a duty to learn and eventually create the environment for your corals to multiply and live. There is a learning curve, so don't get discouraged.
Here are some random observations.
1 your tank seems to be new you still have ammonia, and what seems to be diatoms those are very toxic to corals,
2 you have a mandarin in a tiny tank, they need live food supply, that tiny fish probably needs 200+ gal tank, so is the star.
3 I am not sure how your indoor temperature is , but orlando temperature is 90 degrees, you have t5s on top of the tiny tank, water might be well over 80 degrees , also evaporation of the little tank could give you bad salinity swings.
4. you can benefit from a tiny skimmer, i think there is one on
amazon that looks like your HOB, i would suggest getting that skimmer .
5. Small tanks are harder to maintain than the larger ones, especially that size. You must learn to account for the swings in temperature and the parameters, as well as salinity.
6. You can lower your phosphates with GFO , but for that tank size you can just do a few water changes 30% every 3-4 days.( thats if you have them)
So here are a few things that could be done
1) if its the temperature problem - Add a tiny fan to blow on top of the water , but you will also have to add an auto top-off to counteract the evaporation. ( may be you can come up with some gravity-fed version)
2) Get that little skimmer.
3) remove the goby and the star ( i know it sucks ) wait for your ammonia and nitrites to be completely gone, then get a tiny fish that doesn't grow big and that does not require too much food.
4) and the most important Do several smaller water changes, ( this is everyone's go-to if there are any trouble with the tank.)
