I have a 7 gallon pico with a 2.5 gal refugium that's been running for over a year. All of a sudden I started getting some yellow patches of algae. I siphoned this up and it has come back and continues to get worse. All parameters are normal. Nitrite 0, Ammonia 0, Nitrate 0, pH 8.3, mag and calcium within acceptable ranges. Temp is 77.7.