From my culture manual in the food forum.
A container. Large and low is best
A group of inert, rounded stones; river cobbles is best
An ammonia source
corse sand paper
Sea salt for marine.
Sponge filter, air pump, airline and air stone.
I use kiddy pools on my back deck, but you can use what you like, as long as its low and wide like that. I use fist-sized river cobbles. I sand the 'top' of the stones with coarse sandpaper to rough the stones up a bit so the algae will stick better. I spread them all over the bottom of the pool in one level, except for a corner where I place the sponge filter. I fill the pool with regular, dechlorinated water.
In freshwater you'll need a ammonia source. I use guppies for this. Get good guppies, not the feeder kinds, as you don't want to introduce disease. I use guppies because of their great temperature range: 60 to 90 degrees. I start the air pump. My pools get about six hours of sunlight a day, and indirect the rest of the day.
For marine, I use brackish water, about 1.005 to 1.010, as regular 1.025 sea water just turns green. You don't need an ammonia source, and it'll take you a while to tweak the salt level where the water stays pretty clear and the algae is on the stones.
It takes about three to five weeks to get a good growth on the stones. You could add phosphate and or nitrate to speed things up, but there's no need. I feed the guppies two or three times a day.
The stones are perfect for feeding freshwater fish like Otocinclus and other sucker-mouthed catfish, silver dollars, pacus; lots of herbivore fish. In marine, the algae-covered stones are a natural food source for Tangs, some blennies, some snails; all kinds of creatures in marine and marine reef tanks.
After the stones are picked clean, I replace them in the the pools. In about two weeks they are 'full' again.
Obviously, the bright spring and summer are the best time to culture on stones, though if you have an enclosed porch or sunroom, you can put your cultures there. If a room gets below 70, use a heater for the guppies' sake.
When a finger points to the moon, the imbecile looks at the finger.
Omnia mutantur nihil interit.
The more you read, the more things you will know. The more that you learn, the more places you'll go
I so seldom see my BN attached to the glass, I'm not so sure they even eat algae. They hang in the wood all day and come out for their feast of cucumbers and algae or shrimp pellets. Apparently they get all the alage they need from the stack of wood I have in for them.
Let's just say I don't want to look at algae covered glass to make them happy because I doubt they'd touch it.