Phytoplankton crash????

Can someone help me out. I have just started culturing microalgae to feed my rotifers. started out about 2 weeks ago
everything looked great. Nice green color, on day 9 I split the bottles. Four days later which is today both bottles are clear, and they have a green powder substance at the bottom of each bottle. Any help would be greatful, I need rotifers A S A P, Going to have clown fish hatch in about 3 Days.
Thanks
 
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