Will high levels of NO3 cause any problems?

[joe]

How will high levels of NO3 affect algae if any? I just measured my 1.5ft and it measured almost 25ppm after a 50% water change. Never added any KNO3 except some TMG and K2SO4.

[joe]

some details fo the tank
1.5 x 1 x 1ft
54W light 8 hours a day
DIY CO2
kh - 4
ph - 6.6
fertilisation - 1ml TMG every day, 1/8 teaspoon K2SO4 on mon, wed & fri
fishload moderate - 50 tetras and 5 cories

[budak]

contrary to old thought, no. But you should have enough light, Co2, P, K and micronutrients to sustain healthy plant growth, or else an imbalance favouring algae could result.

Do read through the fertilisation thread entitiled "Planted tanks: Articles on dosing" in the Aquatic FAQ for more information on specific ferts.

Daily TMG dosing!!! Wah, you are hard-core!!

[joe]

thanks budak for the quick reply

the CO2 seems fine with a kh of 4 and ph of 6.6

lights at 54W and so definitely more than 3W/gallon for this tank

micro is dosed thru daily TMG ... hardcore or not not too sure [:]

K is dosed thru K2SO4 ... agar agar only

only thing i never dose is P ... daily feeding of food wafers enuff???

[budak]

just quickly.....

for myself, I found that with adding KNO3 (about 10 ppm weekly), K2so4 (30 ppm weekly), KH2PO4 (2 ppm weekly), plus TMG for micronutrients, algae is rarely a problem. I have not had green spot algae for months, and BBA has been kept down by high Co2.

Try adding a little bit (a rice grain worth) of PO4 to see if there's any effect. YOu do have quite a high fish load for a 1.5 tank though, so maybe half a rice grain might be enough. And keep up your very regular fert regime.

[geoffrey]

Don't push it any higher, it will not be good for live stocks.

[bclee]

Just keep monitoring.

Usually, I find that my tank is more prone to algae when my NO3 reading is high (>30ppm). Algae may not be directly caused by high NO3. But it is an indicator for other problem.

Firstly, you can be having very high bioload or you are overfeeding. Despite the N uptake by plants, the NO3 level remains high due to ammonia from the biological waste from your livestock or excess food. Large amount of waste may lead to potential algae problem.

Secondly, your plant may be having problem uptaking N. Sometimes, the lack of K may reduce N uptake. Deficient in other nutrients may also result in low N uptake.

Thirdly, depending on the type of substrates or substrate fertilisers, you may have some amount of NH3 leaching from the substrate. These could also potently cause algae problem.

In a balance & healthy tank, NO3 level should be under control.

BC

[joe]

Counted again and bioload is 40 small tetras and 5 cories. Feeding is limited to one tablet a day for all of them. Will this be a problem?

Previously when I had APP, they sucked up almost all NO3 and NO3 always stayed below 12.5ppm. Now the APP are all gone except one small patch, and they are replaced by dwarf sag. The APP grew quite well in fact too well. With my K dosing, should I be concerned?

Base fertliser is very thin cos using left overs from my colleague. Probably less then 5mm with 1 inch of gravel. So dun tink have much leeching into the water column.

Will try to measure the NO3 reading again tomorrow.

[sherchoo]

wow.. 40 tetras in a 1.5ft tank is kinda pushing it. In this case, either you reduce you bioload or you increase the water change frequency.

[joe]

Hi Sherwin, do you mean the high bioload will be detrimental to the fishes, or not good for the plants??? So far, no fish deaths except the initial cycling stages.

[juggler]

I agree with Budak on the PO4. N,P,K are macro-nutrients. Shortage of one will affect the uptake of the others. Try to test the PO4 and bring it to 1.0ppm.

I found that since I started dosing PO4, my NO3 levels went down. Apparently the PO4 from fish food is not enough.

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On 10/27/2003 1:48:10 PM

just quickly.....

for myself, I found that with adding KNO3 (about 10 ppm weekly), K2so4 (30 ppm weekly), KH2PO4 (2 ppm weekly), plus TMG for micronutrients, algae is rarely a problem. I have not had green spot algae for months, and BBA has been kept down by high Co2.

Try adding a little bit (a rice grain worth) of PO4 to see if there's any effect. YOu do have quite a high fish load for a 1.5 tank though, so maybe half a rice grain might be enough. And keep up your very regular fert regime.
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[sherchoo]

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On 10/27/2003 10:16:41 PM

Hi Sherwin, do you mean the high bioload will be detrimental to the fishes, or not good for the plants??? So far, no fish deaths except the initial cycling stages.
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yes, it could be detrimental to fishes. Thing easily may go wrong at higher bioloads e.g. if the filtration for some reason breakdown, you may experince NO2/NH4 poisoning. Livestock also have same adverse effects with long duration of exposure to NO3.
For plants, high N may throw your system off balance and algae maybe the results. Have to be careful on this aspect.

[joe]

Thanks juggler!!! Any recommendations fort PO4 testkit since cannot use the search function for now?

Thanks Sherwin!!! I got this feeling the NO3 testkit has expired cos I've had no fish or shrimps problems/deaths for the past 2 months. Hmmmm, does testkit have expiry dates? This one with me for almost a year already.

[bclee]

Joe, don't confuse NO3 with NO2 or NH3. NO2 and NH3 are very toxic to fishes. A few ppm can kill your fishes. NO3 is very much harmless in comparison. Fishes would have no problem up to 100ppm of NO3.

BC

[joe]

Yeah bclee, I understand the differences between NH3, NO2 and NO3. Small levels of NH3 and NO2 will be fatal to most fishes but not NO3. My tank has been cycled long ago and NH3 and NO2 are ZERO, no question about it.