KH Suddenly Decreasing at night - possible reasons.

[Dibi]

Hi everyone,

Below you can see my KH overtime (it is a device called aquarino, a brazillian company developed). It is hard to see, but I can confirm in a datasheet, before my KH used to go up at night and go down during the day.

However this dynamic change, now my kh go up during day and go DOWN at NIGHT.

I changed 30 days ago my ballinh, I was using sodium bicarbonate in part B, now I am using carbonate only.

My PH went to 8.6 at peak from 8.45. This can be the reason?

Thanks for the help!

(I compare the KH device with salifert and hanna and it matches).

 

[Garf]

Hi everyone,

Below you can see my KH overtime (it is a device called aquarino, a brazillian company developed). It is hard to see, but I can confirm in a datasheet, before my KH used to go up at night and go down during the day.

However this dynamic change, now my kh go up during day and go DOWN at NIGHT.

I changed 30 days ago my ballinh, I was using sodium bicarbonate in part B, now I am using carbonate only.

My PH went to 8.6 at peak from 8.45. This can be the reason?

Thanks for the help!

(I compare the KH device with salifert and hanna and it matches).

That's interesting, although I can't read the chart well. It's certainly possible that an event can hinder calcification during the photoperiod, the Bolus Method hocus pocus, for example. Is pH the only change that you know of?

 

[Randy Holmes-Farley Verified Community Expert]

Are you dosing anything during this cycle?

 

[Dibi]

Are you dosing anything during this cycle?

Nothing different. Just ammonia and balling

 

[Dibi]

That's interesting, although I can't read the chart well. It's certainly possible that an event can hinder calcification during the photoperiod, the Bolus Method hocus pocus, for example. Is pH the only change that you know of?

Besides the invert in PH. I raised my nitrates a little bit

 

[Randy Holmes-Farley Verified Community Expert]

Nothing different. Just ammonia and balling

When is the alk dosed?

 

[Dibi]

When is the alk dosed?

24 hours, even parts

 

[Garf]

24 hours, even parts

I suppose you have checked the time settings on your tester, and it's not done something wierd like lost or gained 12hrs.

 

[Dibi]

I suppose you have checked the time settings on your tester, and it's not done something wierd like lost or gained 12hrs.

i did and cross check with hanna and it matches:(

 

[Randy Holmes-Farley Verified Community Expert]

How often does this device measure alk, and do you know how it measures alk?

 

[Dibi]

How often does this device measure alk, and do you know how it measures alk?

It measures hour by hour, like aquawiz, it measures utilizing PH probe.

The thing is that I cross checked with hanna multiple times the last value shown and it matches perfectly.

This morning for example I did this, it measured 7.17 the hanna showed 7.1, so in fact kh is decreasing at night. Because yesterday before night was close to 7.5

 

[gbroadbridge]

It measures hour by hour, like aquawiz, it measures utilizing PH probe.

The thing is that I cross checked with hanna multiple times the last value shown and it matches perfectly.

This morning for example I did this, it measured 7.17 the hanna showed 7.1, so in fact kh is decreasing at night. Because yesterday before night was close to 7.5

If you're dosing 24 equal parts over 24 hours you will see Alkalinity rise at night.

The is very little coral consumption of Alk overnight.

My dosing is configured to dose mostly during the day, with the largest dose at around 2pm.
My lighting runs from 7.30am to 7.30 pm, so peak consumption is around 2pm.

The only way I can see the opposite occurring is a configuration problem.

 

[Dibi]

If you're dosing 24 equal parts over 24 hours you will see Alkalinity rise at night.

The is very little coral consumption of Alk overnight.

My dosing is configured to dose mostly during the day, with the largest dose at around 2pm.
My lighting runs from 7.30am to 7.30 pm, so peak consumption is around 2pm.

The only way I can see the opposite occurring is a configuration problem.

But I am not seeing :(

And I crossed check with salifert and Hanna.

 

[Randy Holmes-Farley Verified Community Expert]

But I am not seeing :(

And I crossed check with salifert and Hanna.

What you cross checked was the day/night rise, not just the matching of values during the day?

This device does not control dosing right, it is just on a timer?

Maybe your device is not doing a good job aerating the samples before the pH measurement. In that scenario, if the pH starts higher (as yours does during the day), it will falsely give it a higher alk.

 

[Dibi]

What you cross checked was the day/night rise, not just the matching of values during the day?

This device does not control dosing right, it is just on a timer?

Maybe your device is not doing a good job aerating the samples before the pH measurement. In that scenario, if the pH starts higher (as yours does during the day), it will falsely give it a higher alk.

I tested in the morning and in the night the last value shown in the equipment and it matched. I didn't tested the 24 values.

The device only measure hour by hour. I checked the device clock and it's right.

Could be a device problem, I will try to test at the peak of my alk to see.

 

[Timfish]

Various organisms will be dissolving any carbonate substrate in your system (sponges, endoliths). These processes will add both bicarbonates and carbonates to your system. You stated in your OP you switched to just dosing carbonate. Have you tried switching back to dosing bicarbonate to see what happens?

 

[Dibi]

Various organisms will be dissolving any carbonate substrate in your system (sponges, endoliths). These processes will add both bicarbonates and carbonates to your system. You stated in your OP you switched to just dosing carbonate. Have you tried switching back to dosing bicarbonate to see what happens?

I didn't. Do you think is the reason?

Is really the only change recent.

 

[Randy Holmes-Farley Verified Community Expert]

I didn't. Do you think is the reason?

Is really the only change recent.

If it is the insufficient aeration issue I posted, then that switch would help cause it.

 

[Dibi]

If it is the insufficient aeration issue I posted, then that switch would help cause it.

Change to bicarbonate?

Sorry I didn't get the correlation the aeration and carbonate/bicarbonate

 

[Randy Holmes-Farley Verified Community Expert]

Change to bicarbonate?

Sorry I didn't get the correlation the aeration and carbonate/bicarbonate

The device you are using MUST fully aerate the test samples to get alk by pH. If that process is incomplete for any reason, then it will report higher alk at higher pH, even if alk is steady. The higher the pH peak, the more it will be off at that peak.

Dosing carbonate instead of bicarbonate raises the pH (as you found), so if your device does not fully aerate the samples it is testing, the switch to carbonate will give false high alk readings when the pH is highest.

Remember, the alk effect day to night you are seeing is fairly small.