High Nitrate Level Found

[eugenecj]

Hi guys, just found high nitrate level in my CRS tank, is it recommended to do a water change immediately? I have Seachem denitrate in my filter, could it be it has exhausted? I never had such high nitrate before.


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[Urban Aquaria]

To reduce high nitrate levels, you should do a series of small water changes over a span of a few days (ie. 10-20% per water change), so that the reduction in parameters is slower and gradual. This is essential for shrimps as they are more sensitive to changes in water condition.

It's possible that the Seachem Denitrate could be exhausted, especially if the tank has been generating high nitrate levels for a while. Nitrate reducing media do have a limit on their efficiency... so the long-term solution is still to find ways to reduce the overall nitrate production, like reducing bio-load, feed less, do more frequent regular water changes, clean the filter more often, add more fast growing plants to soak up the excess nutrients etc.

[eugenecj]

To reduce high nitrate levels, you should do a series of small water changes over a span of a few days (ie. 10-20% per water change), so that the reduction in parameters is slower and gradual. This is essential for shrimps as they are more sensitive to changes in water condition.

It's possible that the Seachem Denitrate could be exhausted, especially if the tank has been generating high nitrate levels for a while. Nitrate reducing media do have a limit on their efficiency... so the long-term solution is still to find ways to reduce the overall nitrate production, like reducing bio-load, feed less, do more frequent regular water changes, clean the filter more often, add more fast growing plants to soak up the excess nutrients etc.

Thanks for the advice!

[WingCher]

Hi guys, just found high nitrate level in my CRS tank, is it recommended to do a water change immediately? I have Seachem denitrate in my filter, could it be it has exhausted? I never had such high nitrate before.


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Hi bro, I am using seachem de*nitrate too and i used to think that it will be exhausted but i found out recently on their website that de*nitrate, seachem matrix and pond matrix are biological media and won't be depleted. The only thing that has exhausted is the anaerobic bacteria colonies living in your seachem de*nitrate. Anaerobic bacteria are the ones that convert the NO3 (nitrate) to nitrogen and oxygen, hence gradually lowering the nitrate level in your tank. I have been told that regular rinsing of de*nitrate can prevent the clogging of pores on the media and thus improving its efficiency, but i have yet to do that.

[Urban Aquaria]

Yeah, when the word "exhausted" is used, it meant to describe the adsorbing aspect of the Denitrate, which has a limited lifespan (denitrate does trap nitrate, but not much)... the majority of the longer term nitrate removing effect is actually done by the anerobic bacteria living inside the Denitrate, they consume and convert nitrates into nitrogen gas and oxides which are presumably used up or diffused into the atmosphere.

Anaerobic bacteria have to live in low oxygen envitonments so you need to use Denitrate in a very low flow filter (ie. less than 200 l/ph, lower the better), otherwise they wouldn't work.

Personally, i have used it for high bio-load tanks before and i basically separate my filtration to 2 filters, one is high flow canister filter for mechanical and biological filtration (that supports aerobic bacteria which convert ammonia-nitrite-nitrate), while for the other filter i use a compact 150 l/ph canister filter just filled with Denitrate, and then tune the flow all the way down until it slows to almost a trickle, that creates the low flow/low oxygen environment for anaerobic bacteria to thrive in (which focus on converting nitrate to nitrogen gas and oxides).

Its all a matter of the ratio between nitrate production vs the nitrate removal by anaerobic bacteria action.... if nitrate production is higher than what the bacteria can handle, it will still keep rising.

So the solution is to either use more Denitrate so that more anaerobic bacteria can colonise it and do their work, or reduce the nitrate production to more moderate levels so that the anaerobic bacteria can handle the remaining amounts.

On the Denitrate bottle instructions, they do also mention that if your nitrate levels are very high, you have to do water changes to lower it to around 20ppm, then the Denitrate will help to reduce it further from there and maintain lower levels (the actual effectiveness still depends on the overall nitrate production rate and amount of Denitrate used though).

[eugenecj]

now i'm confused on what to do, can't decided. i had bad experience in rising my media but adding new media to the tank also have some risk. any final recommendation?

[Urban Aquaria]

now i'm confused on what to do, can't decided. i had bad experience in rising my media but adding new media to the tank also have some risk. any final recommendation?

Its okay to rinse bio-media, just rinse them in old tank water or dechlorinated water, the bacteria will be safe. Rinsing the media periodically will dislodge trapped rotting debris and waste material, which helps to reduce nitrate production too.

Adding new media is okay too, if just topping up, the bacteria from the old media will eventually colonize the new media.

If you are replacing media, then just do it in small batches, maybe 20% every week, so that there is enough time for the existing bacteria population to re-colonize the new media.