I'm still seeing small amounts of algae or mustard algae on the bottom in some spots. I have kept the FC at or above 15 for 2 days and not losing more than .5 to 1 a night. How can I still see some algae? All other readings are normal and CYA around 40-50. pH is a little high, I'm assuming from the high FC. I've brushed and vacuumed almost everyday. Water looks good and is clear. Today I thought, that after I vacuum I pull the hose out and it sits there filled with water. Next day or two I vacuum with all the water still in the hose. Emptied it today after I vacuumed. Could this be the problem?