Here is what worked for my hair algae...
1. Used TESTED RO/DI water (0 TDS)
2. Installed a phosban reactor, using media sold on bulkreefsupply.com
3. Turn the lights out for a few days. Remember, it gets cloudy over the ocean too.
4. Don't feed so much.
5. Consistent water changes.
This is what I did, not all at once, but throughout my years. All seem to make a difference. Hope some or all this helps.
Jame