activated carbon resulting in NO3 rise?

[tasos]

Activated carbon is known to absorb organic substances. Is it possible to absorb too much that they can inhibit NO3-PO4 lowering bacteria. I maybe use a little more than the usual dose. Thank you in advance !

[bertoni]

Activated carbon might be capable of causing some sort of problem like that, but it seems very unlikely at the normal dosing rate. How much is in your system? How often is it changed?

[tasos]

I use one cup every month for 20G aquarium with only live rock and ATS driven by two leds. I added and extra cap because the water was yellow a week after the first addition.My nitrates have dropped close from 30 to zero for the preview month as I started feeding double the amount I used to.Thought it was an accumulation of organics that enabled the biology to retain nitrates.I also placed some pumice rock in the back filter along with the act. carbon, for biological filtering since there no sand in the tank.A week after doing this, my nitrates tested around 20ppm.So I'm looking for the cause (the other suspect is the pumice stone)...

[bertoni]

I suspect the pumice stone a bit more than than the carbon, but either might be the culprit. That's a lot of carbon for a 20g tank. I might start by removing the pumice stone, and see how that helps, but there might be enough bacterial colonization of the carbon to cause problems, at least in theory.

[tasos]

Thank you! I will try to pull the act.carbon first, as it did its job and measure nitrate levels in a week.

[bertoni]

Okay, that seems reasonable to me.

[tasos]

My nitrate levels kept rising, without the act carbon, so it must be the pumice stone.I will remove it and resume to feeding 2-3 day after that.Thank you for the input!

[mcgyvr]

Did you say you started feeding double what you used too?
That can certainly be a cause for higher nitrates..

[tasos]

Sorry, my English is not good enough...When I started to feed more nitrates came close to zero.It is only when I added fresh activated carbon and pumice stone to the back filter that climbed up to 20ppm again.Today I removed the pumice stone pebbles and I placed fresh activated carbon, as the water turned yellow again. The tank has only live rock and a clown fish.No corals to harm with these experiments.

[bertoni]

Okay, the clown fish will be okay with nitrate and yellow water. I hope this set of changes fixes the problem!

[tasos]

Hello again! Nitrate 2-5 ppm in less than 4 days, without the algae in the ATS showing accelerated growth rate. Anyway, it looks too good to be true, so I will look for a new test kit...

[bertoni]

Hmm, I agree that a second opinion might be useful, but that might be accurate.

[tasos]

Update....
Nitrates are high again (between 25-50) after two days. I checked again with salifert and they match.I start thinking I need buying kits for NH3 and NO2 as well to monitor the progress of the full cycle...That is after I changed 20% of the water.There is only one clownfish a brittle star and some snail I added yesterday.Not much of a bioload...

[tasos]

Maybe the disturbances of the biological filter are kicking in.

[five.five-six]

Originally Posted by tasos

Hello again! Nitrate 2-5 ppm in less than 4 days, without the algae in the ATS showing accelerated growth rate. Anyway, it looks too good to be true, so I will look for a new test kit...

Probably a testing procedural error and going from 50~ish No3 to 2~ish in 2-3 days would be really bad. Sea creatures like slow subtle changes.


This hobby requires patience and a lot of it.

[bertoni]

If you are worried about ammonia, then some Prime or Amquel might be appropriate. It's hard to know what's happening at this point. I'd probably do a few 10-15% water changes over the next few days to help clean up any decay byproducts.