high phosphates after blackout for cyano

[MalteseOne]

OK, my tank needs a little advice (again).

I did a 48 hour blackout to get my cyano issues under control.
first 24 hours, changed my 50 micron filter pad because it turned bright red from all the cyano it caught. changed GFO and at lower than normal quantity.
second day, less red, but changed anyways.

this morning, i changed the pad, mostly a dim red grey color and my tank can now be described as more brown than just a red bomb. I thought , darn, that's the first time i did anything on the tank and it worked they way i thought it would.

its now about 5pm, when i normally measure parameters and found that phosphates are 0.276ppm ( 90ppb *3.066 on hanna ULR376).

ammonia forgot to measure.
nitrites 0ppm
nitrates 5ppm
salinity 35ppm (stable for weeks)
pH 8.25 (stable for weeks)
temp 77.5F
tank:200 gallons with 4 tangs, 2 mean clowns, 5 damsels coupled with sps and lps. food is 2 frozen cubes once a day.

before the blackout, the phosphates were slowly rising (GFO was used up) from 0.141ppm. daily change rate was within measurement error of <0.02ppm before the blackout.


now, please tell me the obvious thing i am missing in understanding.

 

[DaneGer21]

Maybe the dying algae/cyano released phosphate when it died? Causing it to jump.

...just spit balling...

 

[Jekyl]

Is this the tank that was just put together in December? I feel like you're doing too much. Raise in phosphate is probably from the cyano die off. How bad of an issue was it? I've had cyano and it goes away on its own usually within a month. Chasing numbers and dosing for everything usually leads to more problems. Do some water changes and get the phosphate where you want it. Large parameter swing may bring the cyano right back.

 

[Mr. Mojo Rising]

I am curious if the blackout worked for you? I thought of trying that in the past but didn’t have confidence it would actually work. Does it work? Thanks

 

[MalteseOne]

Is this the tank that was just put together in December? I feel like you're doing too much. Raise in phosphate is probably from the cyano die off. How bad of an issue was it? I've had cyano and it goes away on its own usually within a month. Chasing numbers and dosing for everything usually leads to more problems. Do some water changes and get the phosphate where you want it. Large parameter swing may bring the cyano right back.

yes, same tank. always had cyano issues.

i wasn't chasing numbers as much as alarmed at the spike. I am ok slowly going along now, but the spike really concerned me that i did something bad.

but the cyano really needed to be handled, it was way out of control. The whole tank sand and back wall were bright red. Normally, i brush and suck it up at water changes to try and control it, but i was gone to texas for a week and employees only feed, so the red really started to magnify exponentially since then.

the picture was the sand a week before.

 

[MalteseOne]

I am curious if the blackout worked for you? I thought of trying that in the past but didn’t have confidence it would actually work. Does it work? Thanks

REALLY worked! look at the thumbnail in previous picture. now look at this picture i just made of same location.