only started like yesterday. wasnt because of the hot spell I think it was the dosing I only use the aquavitro fuel from seachem and my saly is seachem salinity.

What's the reason for dosing. A small WC on a tank that size will easily replenish values

Especialy for LPS and soft corals, they don't need that much.

If it was an SPS tank I would say maybe but surely not for xenia and mush...no need to dose anything, just do water change.

How much fuel did you use? Although its a good source for amino acid, dosing it at full dose can strip the tank from oxygen and can also lead to algae and/or cyano. 1/4th should be the starting dose. And I would never dose amino without strong surface wave or skimmer to replace the oxygen.

But like Titus and Daniella said, not dosing anything and regular WC is always the best idea unless you are confident that the corals you have (LPS and SPS) will use it.