the other thing right now i would be asking myself is if any of my critters are being harmed or in harm right now??
if not then your on the good side of the battle , now time is on your side to start attacking the little things.
post your exact routine including
water parameters(amonia,nitrates,phosphates,salinity,tem p)
pos your equipment and ligts as well.
post what you have in your tank...literally everything that youve added or died.
sand?
this sump you speak of , whats in it and how are you running it??
nitrates are honestly an easy thing to get rid of , just takes some elbow grease and patience
