I wash my mask each morning with warm soapy water, give it a good rinse off and dry with a paper towel, then hang it back on the bedhead ready for the night.
I wash my tank and hose weekly with warm soapy water and give them a good rinse off and paper towel dry.. the tank then goes back in the machine, and the hose hangs vertically to allow any residual water to drip out.
Most machines specify no chemical type additives should be added to the tank, not even eucalyptus oil (which I was going to use to keep my nasal passages clear).
Another cleaning alternative would be a saltwater solution to help kill off bugs maybe.
First, I would use Control-III in my water chamber and on my mask frame, discard my filter, hose, and mask cushion or pillow. Second, I would also insert a removable bio-filter in-line with the hose and mask to additionally trap anything before it got to my lungs. On the Autosense, there is an additional setting in the clinical menu ("AB Filter") that should be set to yes if you insert the filter inline. The filter does not work with climateline. And, it may alter the therapy parameters if it is inserted between the mask itself and hose.
Have you consulted you DME provider for possible professional cleaning.
Are you sure that it is algae and not mold growth from airborne spores. You may want to mention this to your sleep specialist, pulmonologist, or primary care physician as you have a cough. Fungal infections are no fun. Take care and best of luck.
"The object in life is not to be on the side of the majority, but to escape finding oneself in the ranks of the insane." -- Marcus Aurelius