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Innovative Marine Aquariums

Cycling question... odd behaviour with ammonia


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Hello Nano-Reefers, this is my first post and thanks to this page I have ventured into my first reef tank.

Last week I bought a Biocube 14 with a bunch of upgrades and I'mooking for some advice on a situation I have with my reef tank and the nitrogen cycle.

I read most of the topics I could find and couldn't find anyone with a similiar situation.

The previous owner took apart his reef tank and left about 1.5 inches of sand bed in the tank (was still moist) that I lightly rinsed with saltwater prior to adding saltwater and 17 lbs of live rock from Dan at gulfliverock.com.

I added the water, rock etc on 9/19.

Did Ammonia testing on 9/19, 9/21 and 9/24 and the readings were all between 0 and .25ppm... so I was thinking my nitrogen cycle hasn't started yet (I've read about 2 dozen forum topics on it).

Yesterday night I get back from work and notice a rusty color hue over 1/5th of the rocks and about 1/3 the sand's surface, sounds like diatoms to me... so I guess my cycle did start?

This morning I did tested Ammonia, Nitrite and Nitrate...

I'm still showing Ammonia around 0-.25ppm but Nitrite is over 2.0ppm and Nitrates are around 80ppm (attaching picture).

The reason why I didn't test Nitrites or Nitrates the first few days is I went thru the Nitrogen cycle with some new freshwater tanks and the Nitrites and Nitrates were always zero until Ammonia showed up so I thought why waste the test solution.


Is it possible that the existing sand bed that I only lightly rinsed still had enough bacteria to break down the ammonia to nitrite? hence no ammonia spike?

Not sure if I should I introduce bottled ammonia into the system and see if it affects the ammonia levels? or wait until the nitrites go to 0, do a partial water change and assume all is well?

Here's what I have...

My SG is at 1.024-1.025

PH level is just about 8

Temp 78

I've kept the lights on about 8 hrs a day as suggested on this forum.


Thanks all




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Go ahead and keep dosing ammonia until you notice it going from ammonia directly to nitrates within a 24 hour period, and maintaining 0 nitrites.


Once you reach this point, there are a couple different schools of thought. One being to continue the cycle to grow bacteria that can turn nitrate into nitrogen gas.

The other, which is my preferred method, and faster, is to do a 100% w/c to get rid of the nitrates, then throw in some macro algae to take care of any nitrates that may build up in the future with your livestock.


I'm not sure why you are getting those strange levels, but my guess is that it is from the old sand and lr die off. If you continue to feed the bacteria with ammonia, they should find their own equilibrium.

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My API test reads 0.25ppm ammonia on freshly mixed salt wate so take its reading like a grain of salt. My red sea records 0 on my established tank where my API tests 0.25. All the other tests in this kit seam OK.


Another note is that I can't get my freshwater API PH test kit to test within range. I do have hard water but my freshwater tank is a 50/50 mix of conditioned tap & RODI. My tetra kit hits it right at 7.2 and tap high off the chart. Maybe it's my water, who knows, but after these two test I won't be purchasing anything more API.


Once your cycle is over you probably won't need these tests anyway. Pick up Salifert ALK, Calcium, & Magnesium test kits. I wouldn't recommend the Salifert Phoshate test kit as either I truely have 0 phosphate or I just cant see the color - the water looks clear to me, not even a blue tint.


Sorry for the rant... Let me answer your question. The diatom bloom is probably a result exposing silica when your sand bed was disturbed. Relax, your still in the middle of the cycle. After the nitrites return to 0, do a large water change as Nikki suggested, then add your CUC. If your CUC is stable, add a fish. If the fish survives and your levels are good it's time to rock and roll! - just my 2 cents. As per my previous rant, you may never get a 0 ammonia reading on your API test kit. Maybe you should test fresh salt water with it and see if you get 0.25 like I have. :)


It does look like a bunch of macro algae growing on your live rock which will certainly consume your nitrates.

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Matt you're correct about the .25 on ammonia. I get that same .25 color with new saltwater.

I'm going to wait for nitrites to go to 0, do thr water change and give it a few days to see if ammonia and nitrites stay at 0.

Thanks guys

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Just tested the tank.

PH between 7.8 and 8

Ammonia 0

Nitrites 0

Nitrates between 0 and 5ppm - was around 40 ppm 2 days ago


With the Nitrates so low should I do a water change?

Tanks looking pretty clear to me.


Total of 8 days to cycle, I'm going to wait a few more days and add a CUC

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