Okay, cyano bact. can come in different shades of color from brown, rust to purple. Does this algae seem like a blanket on your sand bed or rocks? If it is cyano, you can vaccum it off your sand bed and add something called chemiclean and this will take care of it, just follow the directions on the container. It has worked well for me.
red Slime Algae is an unsightly, aggressive algae commonly found in many saltwater aquariums. These microscopic organisms thrive in underwater environments where excess nutrients and poor water conditions are present.
Red Slime Algae are reddish-brown to purple in color and first appear in your aquarium in small clumps or patches. If left untreated, the algae will spread and form a thick, slimy layer across your entire aquarium.
To prevent nuisance Red Slime Algae from overtaking your aquarium, routine maintenance is extremely important. Here are some simple steps you can take to reduce excess nutrients and organic debris, which play host to Red Slime Algae:
Use a siphon to clean a portion of your substrate regularly. This will remove organic debris and uneaten food. Also, be sure not to overfeed your fish. Only feed as much food as they can consume in a few minutes.
Be sure your aquarium has good water movement. A powerhead or wavemaker will help increase water movement.
Perform regular water changes and routinely replace mechanical filter media.
Maintain proper marine pH between 8.1 and 8.4 with buffers or with kalkwasser. A high pH helps discourage aggressive growth of Red Slime Algae.
Supplement existing filtration with phosphate-removing chemical filter media.
Use a reverse osmosis system for quality source water. This will help prevent buildup of excess minerals in aquarium water from the get-go.
Hope this helps