#hair algae

Hello everyone!! Added an arrow crab to my tank today. He seems to be acclimating well! I bought him to help with bristle worm populations. This guy is pretty small. Any concerns I should watch for in the future? How quickly do they grow? I had a friend tell me in the past they “only eat bristle...

Hello can anyone help me I’m having bad luck with my mixed reef tank lately, diatom’s and hair algae have started to take over my tank I have removed hair algae manually and done water changes but still keeps coming back , also my black long spine urchin has lost all his spines and keeps ending...