Ongoing battle for 6 months now. It leaves at night comes back during photo period. It lives on back glass and some rocks. Feel like I've tried every method in the book. Phosguard, Vibrant, dr tim waste away/re-fresh, 3 day blackout, UV strilizer, Daily manual removal, less light intensity, shortened light period, San sifting goby, microscoped it and had 2 different types. I tried leaving sand bed alone and allowing nutrients to build and it gotten worse, changed filter socks daily, filter pad inside display. I was recommended just now by a friend to take out entire sand bed and let flow for a week before introducing a new sand bed. Thoughts? concerns? advice? anything would be appreciated.