I use kent I do have alittle algae didn't think that would be the cause tho, but i also have two quite large lettuce nudibranches so is see it as more helpful. It can drop 50 to 100 sometimes i guess it changes due to evap. I do bet using the brs is quite cheaper tho, and just wondering you keep your mag up there i always heard to keep it 3 times your calcium am i wrong there. Also i thought of just putting it in my ATO, but i also plan on switching my two part to kalkwasser and don't know the effects of trying this.