Tiny white critters on tank

[urodude]

My new 360 gallon fish only tank is up and running about 4 weeks. Fish are fine. Nitrates/nitrites/ammonia are zero. In the last 48 hours there are thousands(at least) tiny white mobile organisms crawling on the acryllic. Nothing on the fish themselves.
So far people I've asked say its a parasite bloom from the seawater that is not harmful to the fish and doesn't require treatment.
Anyone with other thoughts would be appreciated.

 

[bailey52]

look up amphipods and copepods... turn the lights out and get a flashlight.. hold it on one piece of LR and just watch.. you will see them crawl on the LR they are the size of a pinhead

 

[urodude]

The tank has an artificial reef sculpure(fiberglass), no live rock. The tank was filled with fresh seawater(Live in south Florida)
Just want to be sure they won't hurt the fish

 

[bailey52]

I never understood the real seawater.. I mean its cool.... is the water clear... doesnt it smell at all?? Do you just do water changes with more natural sea water? i live in NJ and I know that the water at the jersey shore isnt clear... I know your in FL

 

[urodude]

We get the water at tide change so its clear. I have a denitrifier on the tank, so water changes are minimal to none.