Algae bloom again!?!

[Crocpete]

My tank is only 5 weeks old and currently only has a small clean up crew. It’s 20 gallon long tank with a 2” sandbed & about 15 lbs of dry live rock. I cycled it with Dr Tims and the parameters have been good. Zero Ammonia, zero nitrates & phosphates, and SG is 1.024. LED lighting on timer and using factory settings. My problem is that I had a lot of diatoms after about 2 weeks, but very soon after a lot of green hair & bryopsis. I use RODI water and have done 2 water changes of 10% in the short time I have had the tank. I finally took the rock out & scrubbed it down and siphoned the sand. In less than a week the green hair and bryopsis is back and getting worse. What am I doing wrong!?! Why does the algae keep coming back! I also have some new stuff on the sandbed. Any advice on how to get rid of this stuff is welcome as well as prevent it from coming back

 

[mta_morrow]

What test kits are you using to measure nitrates and phosphates?

Also, have you been running your lights during your cycle?

 

[KrisReef]

If you only have a cleanup crew, shut the lights off. They don't need light to clean but the algae need light to grow.

 

[count krunk]

started w/completely dry rock? If so, the uglies take a bit longer to go thru.

Without curing of some sort, they can get pretty nasty before they get good.

 

[Crocpete]

I have been using API tests (I know not the best) and yes the rock was completely dry. I have had the lights on the whole time, day & night cycle. I’ve tried turning lights off for 3 days and it didn’t do much, the algae came right back. I would like to get a fish soon and some corals but I am hesitant because of the amount of algae. Should I be concerned? Or am I worried about something that’s mostly cosmetic? What can I do to eliminate what I have and stop new algae from growing?

 

[count krunk]

time.

I would leave the lights off until the rock matures some more. Keep adding ammonia source maybe 2 times a week for 3 weeks or so. Then wait another week or 2. Give the rocks a scrub, do a water change that my be the end of the uglies.

Completely dry starts off quite ugly (algae wise) BRS has some great youtube videos on dealing with completely dry rock, and different curing methods.

Also, you could add a few pounds of some good live rock and that should speed up the ugly phase. But, if it has coralline algae, (which it should if it is good) then you will have to have the lights on some (3 hours should be good) for that to continue to grow/ stay alive.