What am I doing wrong? This mysterious black algae returns overnight all over EVERYTHING!

[strat54]

Hey everyone, glad to finally join the community as a longtime lurker! I'm about 3 months into keeping saltwater, and have not skimped out on effort or discipline. I feel like I'm following everything to a T, but this problem has just been growing over the last month. I am getting very little green algae, the glass needs scraping maybe once a week. But this black stuff covers my sand and rocks, and even closes up all my corals! I go in with the baster almost daily, and it comes back just as bad. It is very likely I am not getting 100 percent of the algae with the baster since a lot of it is in the sand as a result of hermit crabs and pistol shrimp tossing the sand around.

What will ultimately solve this problem? Am I being impatient since this build is basically three months old? Am I overstocked?

I haven't seen anything that matches this exact algae/bacteria in my research and I don't want to start throwing random solutions and make things worse. If anyone can help, I would really appreciate it! I really want to be able to look at my tank and not get a headache!

SPECS:
Fluval Evo 13.5 Gallon
4 hours (blue) + 6-8 hours (white) light per day
Salinity 1.25, daily top off/test (100% Pacific Ocean water plus RODI for top offs)
Nitrates 10, nitrites 0, ammonia 0, PH 7.5-8
Media— two foam blocks. Chamber one floss, carbon, phosphate pads, and bio media. Chamber two is more bio and polishing pad.
Pump is upgraded to Sicce 1.0

STOCK:
2 Oscellaris Clowns
1 Goby
1 Pistol Shrimp
1 Cleaner shrimp
2 Red Leg Hermit Crabs

 

[taricha]

Could be some other things mixed in, but I'd bet that is cyano dominated.

 

[BroccoliFarmer]

I had the same issue. Turned out that my Cheato was too efficient and was sucking out all of the nitrates and phosphates before anything else dependent upon those nutrients could feed. My good bacteria dwindled and my dino's and Cyano took off. Once I started dosing Potassium Nitrate and Trisodium Phospate in my ATO...the issues resolved in a matter of a couple of days / weeks. If you are going to do this..just start low. Depending on the size of your tank and your nutrient uptake levels...very easy to cause a nitrate and phosphate spike.

Rereading your post...what are your phosphates at? My first major outbrake of this took place when i dropped my phosphates to zero. Phosphates ARE needed..just in low quantities. I see you have phosphate pads. Could be source of the issue.

 

[strat54]

I had the same issue. Turned out that my Cheato was too efficient and was sucking out all of the nitrates and phosphates before anything else dependent upon those nutrients could feed. My good bacteria dwindled and my dino's and Cyano took off. Once I started dosing Potassium Nitrate and Trisodium Phospate in my ATO...the issues resolved in a matter of a couple of days / weeks. If you are going to do this..just start low. Depending on the size of your tank and your nutrient uptake levels...very easy to cause a nitrate and phosphate spike.

Rereading your post...what are your phosphates at? My first major outbrake of this took place when i dropped my phosphates to zero. Phosphates ARE needed..just in low quantities. I see you have phosphate pads. Could be source of the issue.

Wow I really didn’t think of that. My phosphates are zero, I put the pads in there thinking better to be safe than sorry. I’ll try removing the pads before I try dosing phosphates.

thanks for the tips!

 

[Sharkbait19]

Yep, the one, the only, the pita Cyanobacteria. I had luck killing it with chemiclean, just remove most of it before dosing.
I agree that it would also be helpful to find the root of the problem, most likely something decomposing and releasing a lot of phosphates.