ChinaRyukin,

I think you could put a small container of clean water or the water from your current ranchu tank (just before you change the water). Put this container under hot sun and then , put some 0.5 table spoon of fish food inside the container. Believe you could get some algae our of it. Important think is the sunlight and the food (nitrate) for the algae.

Hopefully you get the algae within a week.


Ryan