Is this Cyano, Diatoms, ?

[falconut]

I have this crap on my sandbed. It only appears in the areas that receive light. My tank's been up for over 7 years. The sandbed is only between 1/2" to 2". My PO4 tests 0.00 on a hanna checker and my NO3 is somewhere between 0-0.2 using a Salifert kit. I'm running WM Biopellets and GFO and my Mangroves and CHaeto grow slowly. I siphon the sandbed in sections occationally during water changes or sometimes blow it with a turkey baster. I've even tried leaving it alone for a month. I added power heads blowing the area and it even causes bare spots but it still grows in the flow areas. It just keeps coming back. Here are the photos, I guess if I can get it ID'd, that might help more. Here are the photos:
http://i1031.photobucket.com/albums/y374/falconut/mini-DSC_0322.jpg
http://i1031.photobucket.com/albums/y374/falconut/mini-DSC_0323.jpg
Anybody know what this is or how to get rid of it? Everything else looks great.

[ajcanale]

Diatoms, could be a result of the bio pellets? Carbon source is escaping and feeding them, or maybe you have some organics built up in your sand bed that are being released... Do you dose AA'S? I had diatom issues when I increased AA dosing.

[falconut]

I assume AA is amino acids and no I don't dose that. I do get a brownish cloud when I siphon the sandbed. I'm guessing it's organics in the sand. I've read not to disturb the sandbed, I've read to mix it up. I've tried both and this keeps coming back.

[james_wiser]

I have / had a similar issue and the photos look the same

You mention your tank is 7 years old, mine is 3 months so could be different root causes. What I am doing is working, but may not be solving the root cause. And to the question you asked, is it diatom or cyano, someone with more experience should chime in. If I let mine go it would get "stringy". I am inclined to think it is cyano

What I did

increased my clean up crew. More hermits and snails. They do eat this stuff
increased flow. turned up my MP40
I have a shallow sand bed and I do stir it up and vac every 2 weeks with 20% water changes in a 75 gal tall
I run carbon, bio pel and gfo in reactors. My bio pel, just hit the 8 week mark
I do not have fish yet. I am getting ready to add, but I do have several LPS corals on the sandbed and target feed 1 time per week
I reduced my high-noon photo period to 1 hour, but I am going back to 2 hrs using LEDs

I am having success. I do believe it is photo period and nutrient related combined with a stagnate sand bed. If its a shallow bed I beleive you have to get it stirred up with a large enough CUC , mannually stir it up weekly and vac at least every 2 weeks or in realtion to how much nutrient you add to the tank

Have you checked your RO DI filters ? When were they last changed ?

Do you dose / started dosing anything besides ALK, CAL, MAG ?

Im not an expert, just some food for thought as I am fighting a similar issue

[jimsplace]

Had a similar problem, not that bad, but on rocks and sand. I turned the lights out for 3 days problem went away and has not returned. Best thing I ever did!

[falconut]

Only thing I'm dosing is Baking Soda and Calcium Chloride with an occational Tech M. My sandbed cleanup crews don't seem to last. They just seem to fade away and never eat this stuff. I've got BL hermit, still around but never do anything to this stuff. My ceriths and conchs just slowly die again never touching the stuff.

Oh, and my sediment filter was just changed and the carbons are about half life. My TDS reads 0.

[jim t]

Check your temp. I used to get that stuff when my tank would get to 80 degrees and above

[falconut]

My temps shift from 78 to 80 max. They've stayed within this range for a while now.