IME 7-8 hours is plenty. So 13 is definately overkill and will only benefit algae. Plants won't keep growing if you give them 13 hours of light. Once they've had their share for the day they shut up shop, and only algae will benefit from here on as i mentioned. So cutting your phtoperiod down will help a little.
Also the algae your on about isnt caused by too much light, it'll benefit from it but not caused by it. Brown algae, BBA and hair algae all (along with others) occur when CO2 levels fluctuate in an aquarium. You'll be doing this without even realising even if you dont add CO2. Every water change will alter the levels, inconsistent water changes will alter levels. The list is endless, but stable CO2 is key to keeping algae at bay.
As zoddyZod mentioned, your tank isnt mature if its been set-up that long, it is still a toddler technically speaking. We all know toddlers have teething problems
What notg2009 has said i havn't found to work from experience. I was told it wouldnt work, and it didnt and common opinion is that is doesnt work. By all means try it, but you can't 'just' turn off the lights. If your blacking out your tank, you need to black it out fully. Put a black towel over it for a few days and resist the urge to peek. Flourish Excel is a good treatment to try and get rid of unsightly brown algae if you dose it with a pipette directly onto it. Take the water level down and to dose to areas emerged for extra effect.
Then agasin, a picture would help. Theres so many types of algae we could be giving you advice for completely the wrong type.
Hope this helps,
James
