I am puzzled about green hair algae.

Also, my tank will be exactly 1 year old Oct 1st. I started from all dry rock

 

May be turf algae

 

hmm after looking online at some images, maybe that's what it is! Now what?

 

It's not the lights.
No where near enough info here to deduce what's wrong but I would say it's simply dirty water.
It you do enough water changes it would probably rectify it but there are water changes and then there are water changes. If you just take water out and put new in you may just end up going in circles if you're not doing other things like blowing detritus out of the rocks and maybe vacuuming all areas (sump included..possible overflows).
Are you skimming? Use filter socks? Bacteria /carbon dose products?
Everyone has different methods so here is just one mans plan of what I would do.
1. Buy some Prodibio digest. Put one vial in each week and adjust dose after algae is gone. You could use other products like zeobak to do same thing but I prefer prodibio .. it doesn't "go bad" like open container products. Other forms of carbon dose will work but nothing will work as fast as direct bacteria.
2. With pumps full blast stir up /use power head to blow out all detritus so it will flow into filter socks. If you're having a problem.. (which you are) do it every day then after algae gone maybe 1-2 times a week. (of course wash out the socks as the start to flow over)
3. Make sure you have a good carbon running. ROX or Matrix ect. Algae loves gelbstroff.
4. If you're not skimming probably best to use a skimmer.

GFO wouldn't hurt.. and would certainly help get the PO4 down faster.. I don't use it anymore as my bacteria does that job but you may need it if you have that much algae.

 

OK. Thanks. I am making up some water now for another change and I will blow off the rocks etc again, clean stuff the best I can. I usually do it with a turkey baster.

 

Do you think it was pure coincidence that it started just a couple months after I switched from my MH to T5s? Or is it because the T5's are putting out much more of a PAR and glow penetrating the water more?

 

Yeah looks like GHA, an Urchin or Trochus or Abalone would mow that down in 2 weeks.

 

I have a similar problem to the original post and my conclusion after trying pretty much everything is that my rock continues to leak phosphates. My water tests indicate zero phosphate and nitrate. I change about 15% per week, add/replace phosphate remover every 2 weeks, run a skimmer 24/7 add BioMate and ZeoBak and still I have hair algae. I am assuming it will run its course but after 1.5 years I am beginning to think it is time to break the tank down and start again!

 

Think of nutrients as red dye. Then think about how many partial changes it would take to completely remove it. Lots! Algae locks up the nutrients so most people are perplexed when they aren't reading any also most test kits are not accurate at low levels. Once you have the algae it is very difficult to get rid of. Why? Because as you are lowering nutrient levels your algaes begin to die releasing more nutrients back into the water column.
People just don't realise how dirty fish can be and how fast they can foul the waterCarnivorous fish are the worst offenders.Herbivores are much eaxier to clean up after but most are difficult to keep healthy.If you are battling nutrient issues (algae issues)there are lots of ways to do it. My advise is always to lower the bioload or be prepared for an aggressive approach some of which av8 has stated here. This simple equation is the key to successful Reef tanks. Exportation of nutrients must be equal to importation of nutrients. So many people get frustrated and leave the hobby because of the amount of work this entails.They make it worse by chosing too many and/or inappropriate animals.
If you haven't figured out why you are having issues starting over will do nothing but waste your time,money.

 

As far as your rocks leaching phosphates you are right but this happens very quickly as phosphates seek an equilibrium with the surrounding water so the amount in the rocks will be the same as the water very quickly. Removing nutrients is not easy but we have come a long way.Corals will also absorb nutrients for food so adding more can help.