When to dose Alk to avoid pH swing

[clown99]

Need enlightenment. I've been dosing Alk/Ca/Mg 1.5mL/hr, 15 min apart at every hour, starting at 2:00AM to 6:00AM.
From the graph below, on Jan 18 for instance, I noted the times of lowest and highest pH values:
2:30AM 7.94
4:15AM 7.93
6:15AM 7.95
7:45AM 7.93
5:45PM 8.23

So when would be the best times to start & end dosing, if nothing else is changed (lighting, flow, etc)? Thanks in advance.

 

[Randy Holmes-Farley Verified Community Expert]

Dosing high pH additives late at night into the early AM minimizes the pH swing, but dosing any alk additive during the day will minimize the alk changes because it is used more during the day. It's up to you and your system which is more important.

In your case, since the pH low is not that low (not below pH 7.8), stabilizing alk may be more important/useful.

 

[brmc1985]

I agree with Randy. Your PH is fine and you should really look at spreading the doses out through the day to minimize alk swings. What does your alk look like throughout the day? If you have a refugium you could look into running it opposite hours of your display. That will help a bit with the lows.

 

[clown99]

So should I measure Alk during the day to see when the low/high is occurring before adjusting the dosing time?

 

[brmc1985]

So should I measure Alk during the day to see when the low/high is occurring before adjusting the dosing time?

Do you have a trident? Otherwise I would measure through the day every couple hours to see how much it is dropping through the day and which times are the highest usage.

 

[Randy Holmes-Farley Verified Community Expert]

So should I measure Alk during the day to see when the low/high is occurring before adjusting the dosing time?

How much alk do you dose in a day (in dKH)?
If you just spread the dose out through the prime daylight hours, that goes a long way to stabilizing it.

 

[klvnnunez]

Hi,

jumping in here becuase I'm battling the issue. I am using a GHL KHD to dose 4ml of aquaforest component 1+ for alk. I found what my consumption rate is in 24 hours (about 1dkh). I started a regiment of dosing today at 3pm, the ph was 8.4, almost 3 hours later, the ph has risen to 8.6. I'm afraid that if I keep dosing at this rate, the ph will go well above 9. Wondering what would be the best solution as I am running chaeto at opposite light schedule.

 

[Randy Holmes-Farley Verified Community Expert]

Hi,

jumping in here becuase I'm battling the issue. I am using a GHL KHD to dose 4ml of aquaforest component 1+ for alk. I found what my consumption rate is in 24 hours (about 1dkh). I started a regiment of dosing today at 3pm, the ph was 8.4, almost 3 hours later, the ph has risen to 8.6. I'm afraid that if I keep dosing at this rate, the ph will go well above 9. Wondering what would be the best solution as I am running chaeto at opposite light schedule.

pH won't get too high, but if you dose during the night, you can limit the rise (which is rarely an issue and I suspect your pH may be off). :)

 

[klvnnunez]

pH won't get too high, but if you dose during the night, you can limit the rise (which is rarely an issue and I suspect your pH may be off). :)

That's what I thought, about dosing at night but then I realize I will still have a swing during the day becuase of consumption. I was also thinking on dosing on a 12 hour period during the night to minimize the swing. I might change the doe to maybe 1ml every 2 hours.

As for suspecting the ph might be off, I am using the GHL probe for reading. I can for sure calibrate it again. At what point should I get concerned with ph?

I have stopped and changed the schedule to dose at the following hours instead:
10 pm (4ml)
12 am (4ml)
4 am (4ml)
8 am (4ml)

I will keep this schedule and see if the alk stabilizes and ph drops. Then I will test a few times during the day and see if there's an alk drop. If there is, I will dose 1ml every hour or two during the day and see what happens. For example, I've done 3 doses automatically using the old dosing schedule of 4ml every hour the past 3 hours and alk has gone from 7.7 to 8. This means its raising to fast. I have stopped the hourly schedule and I'm going with the schedule above.

I've been having a lot of issue trying to keep alk stable, everything else is fine.