I'm working on setting up my 20 tall creek tank and since I have Greenside darters (or any darters) I figured some greenery would help bring out their colors. I would've liked to do planted but for substrate I'm using coarse gravel from my local creek so that won't work out well with plants. My other option is green algae. But I'm not looking for average soft brown or even the green stuff that grows in spots and is impossible to get rid of. I'm looking to grow some green carpet or hair algae on the rocks so it looks more appealing than average algae and it gives my darters somewhere to hide in. I've never had either of these kinds of algae in any of my tanks so for those of you who have what's the key to growing it?