Have hit a algae/bacterial wall...

[Justfebreezeit]

Do you siphon the sand when you do water changes? Blow off the rocks before a water change?

Could be detritus and uneaten food settling in the low flow areas and fueling whatever it may be. You can always siphon into a filter sock over a bucket and reuse the water if you don't want to do a water change .

 

[DesertReefT4r]

Really looks like cyano to me.

 

[clown and friends]

Really looks like cyano to me.

That’s what I believe as well. How do I combat this stuff?

 

[robbyg]

Whats your water Chemistry Like?
I think it's cyano as well.

 

[Bret Brinkmann]

Looks like cyano with a little diatoms mixed in. I've read from a few people on here that keeping NO3 between 10-15 ppm can help. Personally, my cerith snails take care of any patches that show up. Especially in the sand. I've heard fighting conchs are good at this too. If your flow is lower in that area you can try increasing it as well.

 

[clown and friends]

Whats your water Chemistry Like?
I think it's cyano as well.

Nitrates: 1-2ppm
Phosphates: 0-0.1 ppm (hard to tell with the test I have
Alk: 9.2 dKh
Cal: 460 ppm
The cyano is really only in the low flow area below my single powerhead so maybe getting another powerhead to increase flow would be a fix. I don't understand why I have them because my water chemistry is good and has been consistent like this for several months...help!

Looks like cyano with a little diatoms mixed in. I've read from a few people on here that keeping NO3 between 10-15 ppm can help. Personally, my cerith snails take care of any patches that show up. Especially in the sand. I've heard fighting conchs are good at this too. If your flow is lower in that area you can try increasing it as well.

 

[Bret Brinkmann]

Everyone gets a bad case of the uglys no matter how good they do. All part of maturing a tank. Another powerhead to take care of the dead spot would be helpful with cyanobacteria. It may still take some time to clear up but it should start to improve within a week. Maybe it won't go away completely without something to finish it off like an herbivore or manual removal but it will improve.

Ca and Alk won't have an effect on algae growth other than coraline. Given that you had dinos in the past and you mentioned that your current phosphate tester is difficult to read, I'd recommend a Hanna tester so you can get a clear and accurate reading with the level of refinement needed for phosphate control.