Nitrate consumption and daily swings

[b4tn]

I have been dosing Sodium nitrate for a little over a week now. I initially brought nitrate up to 5ppm and since then things are pretty consistent. I test in the morning and get around 4ppm, dose what should be .5 ppm, test again after and hour and have between 5 and 8ppm. The next morning is always the same result. Last night Around 10pm I was doing my weekly everything testing and nitrate was reading between 20-30 ppm! Strange...I tested again to make sure I didn’t screw the test up and same result. I went to bed and This morning started my normal morning routine. Nitrate is back down to the usual around 4ppm.

So Just because I like to understand things I am doing. What is going on? I’m assuming that daily feeding and fish waste is accumulating during the day and over night corals are consuming the extra? Is it normal for such large nitrate swings Up and back down in a 24 hour period? I have never heard make sure you test nitrate in the morning for an accurate result.

 

[45ZoaGarden]

No, corals really don’t consume much nitrate at all. Algae however does. Corals, like algae, would only consume the nutrients ( like no3) during growth. Corals and algae will both continually grow during the day and night. But here’s where it takes a turn. In order to grow, they need tons of energy for photosynthesis which is obtained by light. They grow much more rapidly during the day and very slow to little growth at night due to absence of the energy source (light). I’m guessing you just had a wacky test. Variables such as fish stirring things up, just pooping, just being feed, you cleaning the tank, not shaking the reagent bottles enough, or not thoroughly cleaning test vials could all throw the test. And yes, all of these variables would cause consistent testing with a reeding of 10ppm because all of these variables would be constant throughout both tests. If it wasn’t simple as a thrown test, it’s bacteria consuming the nitrates. Both possibilities are no big deal . 10ppm of nitrates isn’t bad anyways. I would shoot for 10ppm to give you more room for error.

 

[Randy Holmes-Farley Verified Community Expert]

I think test error is more likely than 20 ppm consumption overnight.

another possibility is a small rise in nitrite for some reason, that falsely read as extra nitrate.

 

[b4tn]

I did a FWE routine Friday afternoon. I expected a spike from die off but didn’t think it would be so soon or drop down low again so quickly. But that could’ve the source of extra.

 

[Randy Holmes-Farley Verified Community Expert]

I did a FWE routine Friday afternoon. I expected a spike from die off but didn’t think it would be so soon or drop down low again so quickly. But that could’ve the source of extra.

The nitrite issue I mentioned seems even more likely then.

 

[attiland]

Is it still happening for you? Have you ever worked out why?

I have just experienced something similar. In the morning tested zero so dosed for 5 ppm. Tested half an hour after dosing and measured 5ppm as expected. In the evening I have tested 20ppm. Ok I have just installed a second wave maker but I was not expecting this high rise from that.

 

[RaymondL]

Is it still happening for you? Have you ever worked out why?

I have just experienced something similar. In the morning tested zero so dosed for 5 ppm. Tested half an hour after dosing and measured 5ppm as expected. In the evening I have tested 20ppm. Ok I have just installed a second wave maker but I was not expecting this high rise from that.

Hi - found the same observation here as well - I thought maybe it was the Hanna Nitrate checker, but as you and I have experienced, Nitrates change throughout the course of the day.

I've never come across this or any reference to Nitrate fluctuations - whether it's the norm or not, I like to find out.

 

[Randy Holmes-Farley Verified Community Expert]

Hi - found the same observation here as well - I thought maybe it was the Hanna Nitrate checker, but as you and I have experienced, Nitrates change throughout the course of the day.

I've never come across this or any reference to Nitrate fluctuations - whether it's the norm or not, I like to find out.

What level of apparent changes do you see during a day?

 

[RaymondL]

What level of apparent changes do you see during a day?

Hi Randy - I posted in another forum asking for thoughts and assistance - this was in regards to the Hanna Nitrate HR checker - my initial thought was that it was faulty because of the swings in Nitrate readings:

0.0
0.16
1.9
and now at 12.1

The first 3 was done within 30 minute time window after a 30% water change. The last value was at about 3.5 hours later.

I believe in my case this is because after the water change the 'chemistry' of the water hasn't had time to stabilize to reflect the true Nitrate value? [Not sure if this is chemically possible.

 

[Randy Holmes-Farley Verified Community Expert]

Hi Randy - I posted in another forum asking for thoughts and assistance - this was in regards to the Hanna Nitrate HR checker - my initial thought was that it was faulty because of the swings in Nitrate readings:

0.0
0.16
1.9
and now at 12.1

The first 3 was done within 30 minute time window after a 30% water change. The last value was at about 3.5 hours later.

I believe in my case this is because after the water change the 'chemistry' of the water hasn't had time to stabilize to reflect the true Nitrate value? [Not sure if this is chemically possible.

Do you recall the timing of the measurements in relation to fish feeding?

At least in baby cod, the ammonia excretion is reasonably slow:

https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1095-8649.1987.tb05257.x

The response to single meals in each case was a rapid rise in ammonia excretion, reaching a maximum 6.5-27 h after feeding, followed by a more gentle decline to a resting rate of excretion. The duration of elevated excretion rates after feeding varied from 19-0 to 95-0 h.

 

[RaymondL]

Do you recall the timing of the measurements in relation to fish feeding?

At least in baby cod, the ammonia excretion is reasonably slow:

https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1095-8649.1987.tb05257.x

The response to single meals in each case was a rapid rise in ammonia excretion, reaching a maximum 6.5-27 h after feeding, followed by a more gentle decline to a resting rate of excretion. The duration of elevated excretion rates after feeding varied from 19-0 to 95-0 h.

Yes, there was no feeding of the fish. I just did the water change - interesting fact about the Ammonia elevation! Well, I'd like to a subsequent test on this - the impact of water change and nitrate levels and timing of

 

[Randy Holmes-Farley Verified Community Expert]

Yes, there was no feeding of the fish. I just did the water change - interesting fact about the Ammonia elevation! Well, I'd like to a subsequent test on this - the impact of water change and nitrate levels and timing of

Great. Let us know what you find.

FWIW, maybe the water change stirred up a little nitrite that showed as a bunch of nitrate.