Cyano??

[bullysam]

125 custom glass aquarium 65x18x24
Sunpower ATI 4 blue+ 2 Coral +
SSA CS8 Skimmer
1 Tunze 6105
Closed loop running two 1" Sea Swirls
Custom sump with three filter socks
Fuge zise in sump 13 1/2 x 8 with 2" deep fiji mud

How do I get rid of the Cyano...is it Cyano?? It's on the sand not the rocks
I stir the sand up everyday and it goes away only to come back next day
Is lights out for 3 days still the right approach??
Salifet test PO4 reads 0
Nitrate Salifert test reads 2

A little backstory...

I neglected my tank for almost a year....maybe three water changes in a span of 9 mos.....stopped dosing....didn't test for anything....slowly stopped caring for it....a few sps colonies that I had died....mostly montis.....except the ORA green psammacora (this thing is invincible) and most zoas survived....I sold off a couple of corals that were still good.....and I put up my equipment and tank for sale but didn't push it.....

Tank and equipment didn't sell....so I really didn't care.....whateve's

Right around RAP ....I started caring again ...so I replaced the T5s that were a year old, I started doing weekly water changes...and siphoning out the red slime that covered the rocks and sand.....after a couple of weeks got rid of the red slime and green hair algae....what I wasn't able to siphon out ...I just threw away....yes I threw away a lot of live rock with dead corals or half way dead corals....so I expected my tank to go thru some sort of cycle again

My tank started looking better so I went to RAP got a couple of frags....started dosing again...started my gfo reactor again...started my GEO bio denitrator again...growing chaeto in small fuge in sump again

 

[bullysam]

forgot to post pic of sand

 

[SantaMonicaHelp]

Yes it is Cyano. I would point a powerhead over the sand that will reduce cyano. Also this may help also:

Nutrient Export


What do all algae (and cyano too) need to survive? Nutrients. What are nutrients? Ammonia/ammonium, nitrite, nitrate, phosphate and urea are the major ones. Which ones cause most of the algae in your tank? These same ones. Why can't you just remove these nutrients and eliminate all the algae in your tank? Because these nutrients are the result of the animals you keep.


So how do your animals "make" these nutrients? Well a large part the nutrients come from pee (urea). Pee is very high in urea and ammonia, and these are a favorite food of algae and some bacteria. This is why your glass will always need cleaning; because the pee hits the glass before anything else, and algae on the glass consume the ammonia and urea immediately (using photosynthesis) and grow more. In the ocean and lakes, phytoplankton consume the ammonia and urea in open water, and seaweed consume it in shallow areas, but in a tank you don't have enough space or water volume for this, and, your other filters or animals often remove or kill the phytoplankton or seaweed anyway. So, the nutrients stay in your tank.


Then the ammonia/ammonium hits your rocks, and the periphyton on the rocks consumes more ammonia and urea. Periphyton is both algae and animals, and is the reason your rocks change color after a few weeks from when they were new. Then the ammonia goes inside the rock, or hits your sand, and bacteria there convert it into nitrite and nitrate. However, the nutrients are still in your tank.


Also let's not forget phosphate, which comes from solid organic food particles. When these particles are eaten by microbes and clean up crews, the organic phosphorus in them is converted into phosphate. However, the nutrients are still in your tank.


So whenever you have algae "problems", you simply have not exported enough nutrients compared to how much you have been feeding (note: live rock can absorb phosphate for up to a year, making it seem like there was never a problem. Then, there is a problem).


So just increase your nutrient exports. You could also reduce feeding, and this has the same effect, but it's certainly not fun when you want to feed your animals