Alk Swing @ Night

[Budman's Corals]

Is it ok for my alk to go from 9.5 in the morning 7:00 am to 8.9 in the evening around 6pm

I dose 210ml at night and was wondering if its better to just spread it out all day long? need some opinions

thanks

 

[Randy Holmes-Farley]

I don't think that swing is a big problem, especially if it happens every day so corals are accustomed to it.

The only way around that is some sort of timed dosing, such as with a pump or limewater on an ATO. But many folks spread out the doses so they do not get such fluctuations. That said, I've not really seen any good data on how much of an alkalinity change in a day is fine and how much is stressful.

 

[Budman's Corals]

Well thanks coral seem to be fine and with me dosing alk at night it helps keeps ph a little more stable

 

[Randy Holmes-Farley]

How do you dose now. A single bolus?

 

[Budman's Corals]

How do you dose now. A single bolus?

I use the apex Dos
I use to use calcium reactor but it really made my ph go low ,also was using 2 chambers with total of 40lbs and kalkstirrer 24x7 thru ato so i went back to 2 part

 

[JimWelsh]

I've very recently been paying attention to the diurnal alkalinity swings my tank goes through, too. I dose DIY 2-part evenly over 24 hours, but still see a swing from a high of about 8.1 at 8:00 AM (shortly before "lights on") to a low of about 7.7 at 11:00 PM (a couple of hours after "lights off").

I found this one article on the subject of diurnal alkalinity changes in natural coral reefs: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4034600/. It has this one graph that shows more or less what my tank is experiencing: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4034600/figure/fig-1/, which is that the alkalinity consumption basically follows the daily light cycle, but there is also a lag period where calcification still continues after "sunset". I'm thinking about switching my dosing schedule to run from about 8:00 AM to about 10:00 PM or so. I'm inclined to believe that maintaining constant alkalinity is more important than maintaining constant pH.

 

[Budman's Corals]

Wow so your dosing during the day when corals are absorbing Alk.. ,I always thought its better to have levels up in the morning and let them consume during day,then replenish at night when resting. Thanks for that info im going to do some reading

 

[JimWelsh]

To be clear, I'm currently dosing evenly over 24 hours. I'm contemplating changing to dosing during the day (and during that "lag" time after the end of the day), when consumption happens.

 

[Randy Holmes-Farley]

To be clear, I'm currently dosing evenly over 24 hours. I'm contemplating changing to dosing during the day (and during that "lag" time after the end of the day), when consumption happens.

Do you know about how much total alk you dose each day?

 

[JimWelsh]

Do you know about how much total alk you dose each day?

180 ml of your Recipe #1, or appx. 340 meq into appx. 210 gallons of water volume, so about 0.42 meq/L/day.

 

[Randy Holmes-Farley]

Interesting. So that's about 1.2 dKH per day of addition or 0.05 dKH per h (assuming it is completely even). You see a rise of 0.4 dKH from 11 to 8 or 0.044 dKH per h. I think you've mentioned this in the past, but I didn't recall the values being so close.

So I agree that switch to mostly of completely daytime dosing might make sense since it seems nearly all of the consumption in your tank is during the day.

 

[JimWelsh]

That was my thinking, Randy. And I suspect that my tank is probably typical in that regard. However, reading through the article I linked above, "Results of this investigation demonstrate the difficulty that corals encounter in shedding waste protons generated during calcification. High rates of H+flux continued for several hours following peak Gnet" and, "...corals can cope more effectively with the problem of DIC supply compared to the problem of eliminating H+." The conclusion of the authors in this study is that pH is a bigger issue for the corals than alkalinity. Food for thought.

 

[Rob Lion]

@JimWelsh did you ever change your dosing schedule to follow the lighting schedule with a lag?

 

[Hausser]

I as well changed up my dosing schedule due to my ALK consumption. I use to dose at 12:00am and switched to start my dosing when lights turned on at 2:00pm. My tank uses 1.1 DKH a day. I noticed by switching my dosing I had less of a swing through out the day. I dose 400ml of ALK a day using Randy two part recipe #2, my doser doses my tank every two hours.

 

[Rob Lion]

any change to your pH stability @Hausser ? and have you had any RTN or STN?

 

[Hausser]

No changes to my PH swing, I have not had any RTN or STN.

 

[Rob Lion]

OK many thanks, I'm about to change my Alk dosing schedule to follow my lighting schedule 7 am - 7pm, But in the last couple of weeks I have had 2 RTN on Acros, the only difference was that I had moved to daytime dosing from 9am - 5pm.

 

[Hausser]

Check for bugs, my tank was all good then all of a sudden I lost some coral to RTN and come to find out some how I got red bugs. You shouldn't have tissue loss to changing dosing times. Corals consume a lot more ALK when lights are on versus off. Have you tested your ALK with a different test kit? I use Red Sea and other people I know had a Red Sea ALK test kit that was 4 DKH off.

 

[JimWelsh]

@JimWelsh did you ever change your dosing schedule to follow the lighting schedule with a lag?

No, I did not. I have since re-aquascaped somewhat, about two months ago, removing some very large Montipora and Seratipora, and as a result, my alk consumption was cut almost in half. But I still have been contemplating making that change once my consumption goes up again.

 

[Rob Lion]

yep, done all the checks, dipped with Rx Pro etc... test with salifait and red sea test kits. The only 2 things that had changed were,
1) i moved from night dosing to day,
2) I removed a large clunk ( 50% ) of Caulerpa from the refugium.