Diatom Confusion

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About a month ago i added a few new rocks to my tank and coraline has being slowly creeping onto it i would say over 60% of the rocks are now covered with coraline. so about a week ago i had a major nithrait boom. went from around 10 to over 80 like in 2 days. so i did a major WC but did not clean no media glass nothing.. no surface area was touched only a 80% water change. i though all was well. but i notice this morn i had a little Diatom on a rock.. i didn't think twice about i. so i left to take care of a few things.. got back like 30 min ago and all rock and glass is covered in diatom. not the coralline area but any exposed area is covered. but none on the substrait. my tank has been estrablished for over 4 years. other then the rock added like a month ago nothing new added to environment. so my question is,, well hell a few questions. why does it seem my tank is recycling? (only water bacteria was removed) why is it covering everything except my sand? and also my rocks that the Diatom its over taking. will they stay stained like that or after it cycles again. the brown diatom color will fade away and let the coralline finish covering it. I feel like im back at the beginning.
 

Jonify

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I'm not sure, but with an 80% water change, it's possible that the drastic shift in water clarity allowed more light to enter the tank and fueled a bloom of diatoms (which should go away eventually, once you get your nitrates down to below 2.0 ppm).

The massive influx of trace elements with an 80% water change might have exacerbated that, but the science is less clear on that, so who knows. Small water changes don't impact clarity and the penetration of light into your tank that much, but something like an 80% change is a drastic move than can have a huge impact on PAR levels.

Until your established bacterial colonies can catch up to the processing of biological matter thriving in the new PAR levels, diatoms will be a thing (and other possible uglies). I'd avoid changing out that much water in the future, and look at other ways to bring down nitrates; things like feeding less, cleaning out your sump (with a 4-year old tank, there's likely a lot of sediment and detritus in your sump/filter/sandbed), dosing Red Sea NOPOX daily to lower nitrates and phosphates, improving the efficiency of your skimmer, vacuuming your gravel consistently, and doing smaller water changes more consistently and frequently. With more established tanks, lowering nitrates isn't best achieved by a large water change.
 
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90G Mark

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I'm not sure, but with an 80% water change, it's possible that the drastic shift in water clarity allowed more light to enter the tank and fueled a bloom of diatoms (which should go away eventually, once you get your nitrates down to below 2.0 ppm).

The massive influx of trace elements with an 80% water change might have exacerbated that, but the science is less clear on that, so who knows. Small water changes don't impact clarity and the penetration of light into your tank that much, but something like an 80% change is a drastic move than can have a huge impact on PAR levels.

Until your established bacterial colonies can catch up to the processing of biological matter thriving in the new PAR levels, diatoms will be a thing (and other possible uglies). I'd avoid changing out that much water in the future, and look at other ways to bring down nitrates; things like feeding less, cleaning out your sump (with a 4-year old tank, there's likely a lot of sediment and detritus in your sump/filter/sandbed), dosing Red Sea NOPOX daily to lower nitrates and phosphates, improving the efficiency of your skimmer, vacuuming your gravel consistently, and doing smaller water changes more consistently and frequently. With more established tanks, lowering nitrates isn't best achieved by a large water change.
Thank you, looking back such a huge WC was a bad idea.. its i have been so good at keeping a low nitrait level. once i seen it climbed so high. I,, ummmm, well I just panicked. thanks for some scientific knowledge have a good day and stay safe.
 

Jonify

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Thank you, looking back such a huge WC was a bad idea.. its i have been so good at keeping a low nitrait level. once i seen it climbed so high. I,, ummmm, well I just panicked. thanks for some scientific knowledge have a good day and stay safe.
Oh for sure--I'd have panicked, too. We've all been there, and will probably be there again very soon. :p
 

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