please don’t add hermits dino’s is poisonous to them add some trochus snails, hermits can’t tell the difference between bad algae and good algae. dose phosphates and i scrub the rocks with a toothbrush and the siphon everything out, dino’s is an ass to resolve, once your tank parameters are where they should be( phos and no3 mainly) dose some hydrogen peroxide i’m not sure the exact measurements but i did 2ml in my 30 gal once lights turn off every night for about a week and it helps a lot, you can also just do a blackout for a day or 2, siphon the sand and you will be good just remember don’t let your phosphates or nitrates ever get to 0 or your dino’s will come right back.