Hi, looking for some advice please. Seem to have mould in the flow frames and cannot remove it. Have tried jet washing, scrubbing with diluted bleach and using a cotton bud but no luck. It seems to be in a few of the frames. We removed the outer frame which was the worst affected. We have removed the tray underneath to improve ventilation. It is not a thick mould but like a black layer in the cells. We check the hive frequently and there is a healthy population. There is honey and activity in the unaffected frames.
Any advice would be greatly appreciated. Thanks