Never ending diatoms and cyano

[Bbio]

4 month old tank. I had a diatom bloom, then a GHA bloom, then it all went away and was clean for about a month. My Nitrates bottomed out Then the red spirulina Cyanobacteria immediately started growing. I remove it by hand and it starts coming back the next day.

I decided to raise my nitrates with neonitro. I raised them to 10ppm over the course of a couple weeks as my phosphate was 0.15. When I got the nitrates to 10ppm, my phosphate dropped to 0.01 and has steadily been climbing on its own.

When I raised my nitrates, it seems to have fueled the cyano and the diatoms of old came back in full force again.

Now I have cyano and diatoms again. I was only cleaning the glass once every 4 days, and now I also have to clean it twice a day as the film on it grows back rapidly.

 

[KrisReef]

4 month old tank. I had a diatom bloom, then a GHA bloom, then it all went away and was clean for about a month. My Nitrates bottomed out Then the red spirulina Cyanobacteria immediately started growing. I remove it by hand and it starts coming back the next day.

Your post title indicates to my old, old fish keeper mind that you have not been keeping reefs for too long? That’s how we all start and I hope to encourage you by saying that you may soon find that the tank starts hitting its stride and these growing cycles will mature if you are able to keep active with routine maintenance. The tank looks pretty good now as a start to a beautiful healthy ecosystem.

I decided to raise my nitrates with neonitro. I raised them to 10ppm over the course of a couple weeks as my phosphate was 0.15. When I got the nitrates to 10ppm, my phosphate dropped to 0.01 and has steadily been climbing on its own.

I took many years to realize what you described in this paragraph. The nitrate and phosphate levels can be seen working together, the metabolism and uptake of phosphate requires available nitrogen for the microbes to utilize PO4. Figuring out how to feed the system so that these nutrient levels stay available and stable (sometimes called “balanced “) is where you might focus now so you can feed the system with confidence that nothing is starving or being over fed.

When I raised my nitrates, it seems to have fueled the cyano and the diatoms of old came back in full force again.

Now I have cyano and diatoms again. I was only cleaning the glass once every 4 days, and now I also have to clean it twice a day as the film on it grows back rapidly.

This struggle is necessary for the short term and it is a natural progression that you can take control over, eventually. I can’t say how long it will last? You have to make changes and adjustments, and observe what happens. Keep a journal, write down the date of your change or input and try to make only one change each time. Then watch, check parameters and observe trends. Resist the urge to change multiple variables,(Food, water changes, adding new equipment, new livestock, can make tracking the progress impossible!)

It’s difficult to slow down and stop building a reef, but I am encouraging you to do this now and once you get a handle on what you have, and how to keep it clean and nutrient balanced then you can move forward with more control and confidence to build it out with positive results.

It’s really off to a good start. Patience and focus for the win.

 

[Bbio]

Dad? This reply brought be back hope. Thank you. Things seem to be going down hill

 

[Ryanliyikun]

That sounds like classic nutrient instability in a young tank—you basically swung from ultra low nutrients to rapid dosing, and now everything (cyano + diatoms) is taking advantage of it. When nitrates bottomed out, cyano moved in, and then bringing nitrates up quickly while phosphate dropped created another imbalance.
I’d stop chasing numbers for a bit and focus on stability—hold nitrates in a reasonable range (like 5–10) without big swings, let phosphate settle naturally, and avoid aggressive adjustments. Keep up manual removal, normal water changes, and consistent lighting/feeding. These blooms are super common around the 3–6 month mark, and they usually burn out once the tank stabilizes

 

[Bbio]

That sounds like classic nutrient instability in a young tank—you basically swung from ultra low nutrients to rapid dosing, and now everything (cyano + diatoms) is taking advantage of it. When nitrates bottomed out, cyano moved in, and then bringing nitrates up quickly while phosphate dropped created another imbalance.
I’d stop chasing numbers for a bit and focus on stability—hold nitrates in a reasonable range (like 5–10) without big swings, let phosphate settle naturally, and avoid aggressive adjustments. Keep up manual removal, normal water changes, and consistent lighting/feeding. These blooms are super common around the 3–6 month mark, and they usually burn out once the tank stabilizes

Thanks. I needed that. My softies are also not looking so well. My nitrate is holding at 10 and my phos is fluctuating from 0.01-0.03 almost daily.

My ding dang never opened up and now my GSP and gorgonian have half their polyps closed and my 2 pipe organs look shriveled with skinny polyps.




This was my PAR mapping without lid but I’m using egg crate as a lid so I figured it also might be too low, so I’ve been increasing intensity 5% per week every Sunday. I went from 60% to 68% in the past 2 weeks