should I be concerned?
 

My tank has been up and running for about a year now and everything seems to be ok, however my question is in the last week I seem to have an explosion of "seaweed" or "green algae" growing on my live rock all of a sudden, Is this normal or should I do something?
Bruce

What kind of lighting, and have you changed the bulbs lately? Have you measured your nutrients? Anything missing in the tank? I'd say ya, be a bit concerned. Not emergency stuff, but you want to get on top of this.

I also see you're looking for more rock. Have you added any new (used) rock lately?

no I haven't added any new rock since I started my tank

regular water changes will clear that right up

I have the standard t5 lights and the bulbs were replaced about 2 months ago. everything measures ok so thats why I little concerend

K, bulbs sound fine. "Measured ok" is how many PPM of NO3 and PO4?

Any livestock missing? It doesn't take much to raise phosphates in a tank.

what are your water parameters? Are your nitrates creeping up?

RO water? If so your filters might be in need of a change.

Can you provide photos of the algae?

While it is true that many GHA issues can be resolved by lowering the nutrients in the system, there are some that are able to grow exceedingly well in lower nutrient environments: bryopsis and debersia, which are both green "hair" algae being two of them (though bryopsis is the more difficult of the two to get rid of).