What the hell is going on in my tank?

N

Niglin

New Member
I've had this algae (diatoms?) growing like crazy for the past while in my 100 gal. The tank is established - 3yrs old, with 30% water changes done bi-weekly; parameters on master test kit are in the normal range : RE: ammonia, nitrates etc (lighting about 1w per gal). I have attached/running a reef octopus skimmer and an aquaclear filter with phosguard and active carbon as media. In any event, I have to clean the sh**t of the rocks and glass twice a day (seee attached photos), I'm stumped because nothing has much changed in 3 years and this came out of the blue. I do not want to get into buffering the water with chems (as it's killed my fish in the past), rather to address root problem(s). Any ideas reef gang? Thanks.


Niglin
 

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beaslbob

beaslbob

Well-Known Member
looks and sounds like cyanobacteria to me.

What can happen is nitrates are reduced by low oxygen bacteria but not so for phosphates. So after some time (usually 6-9 months) the tank can become nitrates starved. especially at the top of the sand bed and on rocks where there is low oxygen content.

So your tank goes along things really really look great, nitrates finally come down and then here comes the cyano. They can use nitrogen gas (the end product of low oxygen bacteria reducing nitrates) for their nitrogen. And get the phosphates and use co2 as well. And in the process take nutrients away from the algae/coral. So the tank becomes cyano dominated vrs algae/coral dominated.

One thing to do is to simply kill your lights. The cyano dies off returning nitrates to the system for the algae to feed on. Then resume with less lighting and adjust so the algae/corals thrive and the cyano stays away.

If you don't have then add a refugium with macro algae. If you have macro algae try to maintain the tank to favor that algae.

To me bottom line your tank is a little out of of balance favoring the cyano. The goal is to rebalance the system to favor the algae corals again.

my .02
 
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