Green algae on sandbed that creates stiff layer

I have had my setup for about two months. I have in the last 3 weeks, started to get green algae on the sandbed. I try to keep it stirred up, but it appears to created something like a film or layer of attached sand on the top. I have to aim a powerhead really close to it to break it up. But it reappears the next day. I am only running my Halides for 6 hours... nothing else. Any advice would be appreciated...

Ammonia = 0
Nitrite = 0
Nitrate = 2.5 ppm
PH = ~8.4

Also Let me know what you think about the setup.... I'm new at this ;D

 

Looks like Green Cyanobacteria and you should suck it out when ever it appears. Just my opinion but looks like you have quite a few fish for a 2 month old tank. I would fed lighter and keep up on water changes. It just looks like new tank syndrome to me. Sure there might be someone with more experience to respond also.

 

Thanks for the advice. I got fully cured rock and let it cycle for a month before getting fish. I then got a pair of percula clowns and a very small blue hippo. I just recently (three days ago got the large Naso) because it was a steal 50 bones, and it is about 7 inches. The algae on the sand was happening prior to that. Everything seems healthy. I just need to know if this is a cause for concern.

 

I would just suck it out each time it builds up. It toke my tank with a 6 inch deep sand bed about 6 to 8 months before I stopped getting it.

 

All you need is some cerith snails

 

not to sound mean but no matter how great a price a fish is should not influance your purchase. Your tank is very young and you could be endangering your new fish. Take it slow. This could be another reason you are having cyano out breaks.

 

Your tank is as stocked as a tank that is about 2-3 years old. Even a pair of percs at 2 months is a lot for a 2 month old tank. Your tank is still cycling. For a large tank like your's, it will take a good 2-3 months alone just to fully cycle the tank to be ready for a damsel. To put in perspective, I just restarted my dead 150G tank and have been cycling it for 4 months now and still waiting to put fish in it due to my nitrates. Just curious, how big is your tank? It looks about 100G or so? How is your skimmer producing?

 

It is 120 gallons w/ 50 sump. It appears to be fully cycled and has since about a week after putting in the LR. No real ammonia, Nitrite, or Nitrate to speak of. The skimmer is getting a great deal of green/brown junk.

 

You have anouth aerobic bacteria to break down the NH3->NO3 but not enough anaerobic bacteria to break down the NO3->NO2. The cyano is using the excess NO2 to grow, which is why you are reading zero NO2. Stagnant water is a real enabler of cyano, increase the water flow to the area it is growning and that usually will help your problem.