dark algae & adding sand

[BigJim]

So I have two issues in my 150g reef w/ normal params (phosphates were high but are being dealt with and have been reduced).

1. I have had a problem with a dark green (almost black) algae on the sand. It has been ongoing for 6 months. The algae is a thin mat only on the sand bed. I've tried manual removal as well as siphoning but it comes back within week. I've never seen any other posts on this type of algae, it is not green hair algae or red algae, it is very dark. Any suggestions on how to get rid of it or are there any critters that will consume it? My snails don't touch it. On a side note, has anyone ever dealt with a pink algae that looks like cotton candy? It comes and goes, I'm not sure if these two algaes issues are related. I dose vodka and the pink algae has been a result.

2. My second issue is a result of the algae. When trying to siphon it out, I've also removed a lot of sand. What is the best way to add sand to an existing tank w/out it clouding the tank or going all over the place.

<a href="http://s73.photobucket.com/albums/i220/divide45/?action=view&current=algae1.jpg" target="_blank"><img src="http://i73.photobucket.com/albums/i220/divide45/algae1.jpg" border="0" alt="Photobucket"></a>

<a href="http://s73.photobucket.com/albums/i220/divide45/?action=view&current=algae2.jpg" target="_blank"><img src="http://i73.photobucket.com/albums/i220/divide45/algae2.jpg" border="0" alt="Photobucket"></a>

 

[smartreef]

looks like tank needs more flow/ what type skimmer?

 

[BigJim]

The tank has been running over 3 years.

AquaC EV150 or EV180, I can't remember which. For flow, aside from the return holes predrilled in the tank, there are two Koralia powerheads. When directed at the sand they just blow it around.