In a normal fish less cycle with dr time one and only where does the phosphate usually come from?Bacteria need phosphate to grow.
I had the same thing happen to me when I restarted the my Fiji cube last year, I dosed up phosphates until they were detectable every day and carbon dosed, it cycled in a couple days.
telegrham tested mb7 along with a few other bacteria products, short story, its not worth buying which is my experience too.
The dry rock/sand may even bind some ammonia too idk but all I know is dry rock can be a pain.