You are doing things that even seasoned keepers do not do in a tank that has no coral in it.
Go back to water changes, change out the whole volume over a couple days. Test, test and re test and then get someone else to test for you.
Check everything, no you wont feel stray voltage if you have it.
You are fixing to have to turn over every rock to see if you do not even have some coral eating monster hidden in your tank that is devouring everything at night when you sleep.
This is definitely odd.
I was thinking light acclimation but now, I am not so sure.