Irregular Nitrate level

[MikeKoh]

The whole of last week, my nitrate reading is zero. After 50% water change last sat. I added 60ml of Lushgro-aqua (640litres of tank. The nitrate went up to 5ppm. On Monday, it dropped back to zero. My phosphate is >1ppm (used 3 teaspoon of potassium phosphate..I think I overdosed). Tuesday, my nitrate went up to 40ppm! Is it practically possible for one to maintain a regular nitrate level at 10ppm.

Has anyone else experience nitrate swing from zero to 40ppm in 24 hrs in a large tank of 640 litres of water?

I am just thinking.... to add more nitrate, can I just put a market prawn in the filter so it wont get eaten...but as it decompose, the BB will convert to nitrate.

[vinz]

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On 11/26/2003 3:22:43 PM

The whole of last week, my nitrate reading is zero. After 50% water change last sat. I added 60ml of Lushgro-aqua (640litres of tank. The nitrate went up to 5ppm.

Makes sense, LGA (LushGro-Aqua) contains Nitrate.

On Monday, it dropped back to zero. My phosphate is >1ppm (used 3 teaspoon of potassium phosphate..I think I overdosed).

NO3 used up in 2 days... possible if you have good growth. Excess PO4 is ok.

Tuesday, my nitrate went up to 40ppm! Is it practically possible for one to maintain a regular nitrate level at 10ppm.

Yes, you should be able to maintain consistent levels if the tank and its routine is stable. NO3 levels will fluctuate a little as they get used up and replenished by dosing/feeding. The fluctuations you have described are way out.

Has anyone else experience nitrate swing from zero to 40ppm in 24 hrs in a large tank of 640 litres of water?

Did you mix/shake the test solutions properly between reagents? Perhaps a piece of uneaten food/dead fish lost somewhere in the tank? Any change in plant mass (pruning), fert regime?

I am just thinking.... to add more nitrate, can I just put a market prawn in the filter so it wont get eaten...but as it decompose, the BB will convert to nitrate.
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Not a good idea. Ammonia can trigger off algae blooms. I'm not sure if the bacteria and plants can take up/convert the ammonia fast enough. Second, uneaten food feeds other organisms in the tank. You might find your tank infested with planaria and other worms, etc.

[MikeKoh]

Just measured my nitrate (wed), it is now at 5ppm. I did removed all my tenellus. Decided to try all hairgrass as foreground. Maybe that's why the swing.... but seems that the remaining plants are really sucking up all the nitrate. Last 2 weeks were 0 nitrate all the way, even after I added in Seachem's nutrients.

I think I have to look for potassium nitrate.

[MikeKoh]

Now... I always read that we should use phosphate to limit the nutrient uptake (or am I wrong).. can we use Nitrate as the limiting nutrient instead. Example... I dose K and fix my PO4 to 1ppm. I then measure and slowly dose my NO4 to 10ppm. Comments?

[bclee]

You should not try to limit the plant by any nutrients. You might end up with algae problem. Just dose accordingly to keep PO4 @ 0.5-1ppm and NO3 @ 5-10ppm.

BC