Cyanobacteria starting on sandbed

kalinowskiz · May 6, 2020

Hi everyone just looking for a little advice i have a 75gallon tank mixed reef. I dont have a ton of coral in it just yet just some softies and lps no sps. I had a nitrate spike and was testing it with an api kit giving me readings at 160ppm. So I have been vodka dosing for four weeks now adding 2.1ml a day and I did a 20% water change and vaccumed the sand about a week and a half a go which brought my nitrates down to 40ppm not sure if it is a combo of the dosing and the water change, but that is where i stand with that. My phosphates are at .25ppm and now this past week I have noticed I am getting cyanobacteria forming on my sandbed which is making me nuts. Nothing is growing on my liverock but I dont know if thats because my trochus snails and blue legged hermits are handling that. I am wondering if any of this is due to the vodka dosing. My pH is stable at 8.1, ammonia 0ppm, nitrites 0ppm, calcium usually between 450-480ppm, alk is usually 11dkh when i do a water change then rises to about 12dkh for some weird reason I think is due to dropping nitrates, and my mg is usually between 1360-1400ppm. Any help you could give me on this would be greatly appreciated. Thank You.

myinvalidname · May 6, 2020

A nitrate spike to 160 ppm is huge. I’d start with did something die to cause the nitrate spike or is this actually a cumulative effect of over feeding and not a spike.

I’m not against chemical treatments for cyano. But dropping the NO3 and PO4 should help. Is the cyano in a low flow area? Increasing the flow can sometimes be helpful. I’ve also been able to decrease the red spectral intensity of LEDs and reduce Cyano. If you can you can do a blackout for a few days; this depends on the type of corals you have. Although if you do a blackout without lowering the nutrients, then it’ll likely come back.

kalinowskiz · May 6, 2020

myinvalidname said:
A nitrate spike to 160 ppm is huge. I’d start with did something die to cause the nitrate spike or is this actually a cumulative effect of over feeding and not a spike.

I’m not against chemical treatments for cyano. But dropping the NO3 and PO4 should help. Is the cyano in a low flow area? Increasing the flow can sometimes be helpful. I’ve also been able to decrease the red spectral intensity of LEDs and reduce Cyano. If you can you can do a blackout for a few days; this depends on the type of corals you have. Although if you do a blackout without lowering the nutrients, then it’ll likely come back.

I thought the same thing thats why I did a water change and a overall cleaning on the glass when I did that i did find about three empty snail shells that must have died and have been hiding in spots I could not easily see. So I wound up removing those and have been monitoring the nitrates since and they did drop dramatically from 160 to 40ppm. Before I did the water change though I had 0 problems with cyano. So I cant figure out why after I finally started lowering my nitrates that I am getting cyano. As far as my corals all I have currently are a couple of kenya trees some zoas/palys, a bubble coral and a torch frag. I have the kessil a360x lights and I am only running red at 20% at most so I am wondering if I should turn that off.

myinvalidname · May 6, 2020

It’s possible that the 160ppm was a measurement error. I’d be surprised if the tank could use nitrate that fast.

Carbon dosing generates bacteria. Are you removing this via a skimmer? It’s possible that the organics from dosing and un removed bacteria could drive cyano.

kalinowskiz · May 6, 2020

myinvalidname said:
It’s possible that the 160ppm was a measurement error. I’d be surprised if the tank could use nitrate that fast.

Carbon dosing generates bacteria. Are you removing this via a skimmer? It’s possible that the organics from dosing and un removed bacteria could drive cyano

I am not a fan of the API nitrate kit I feel like its hard to tell the colors once it gets a little high, thats why i ordered the red sea pro kit which I am still waiting on. I am skimming and collecting a good amount but maybe i could try to tweak my skimmer and see if that helps to skim some more.