Alkalinity Swings ?

[CarolinaReefs]

I have been in this hobby for a while and have learned a lot and I will always have more to learn. I read a lot posts where people say that stability, especially ALK, is very important. You hear the phrases "ALK swings" and "ALK spikes" used frequently but, doesn't ALK always go down unless you are adding ALK to the tank? I'm pretty sure that ALK doesn't "swing" like pH does due to biological proceses and CO2 levels in the tank. Please correct me if I am wrong. I can take it and I am eager to learn the facts. I kind of interpret "ALK spikes" as meaning that the user has added too muck ALK supplement at one time. The only other ways I could see ALk rising is from changing water with new water that has a higher ALK content or using some sort of Man Made rock that used cement or some other similar type of material without "curing" it.

What do you guys think?

 

[Randy Holmes-Farley Verified Community Expert]

Alk has a fairly steady decline between doses, perhaps mostly during the day and less at night. The concern with smallish changes is, IMO, not important for all tanks, but may be important for SPS tanks and may be especially important in low nutrient tanks.

Swings can come, for example, by not dosing frequently enough. If you lose 1 dKH per day and dose once a week you will see a substantial swing. Some folks claim that dosing many times per day and keeping alk very stable leads them to observe that their tank seems "better" than if the only dosed once a day.

 

[reefwiser]

What you need to do is study your tank taking alk readings morning mid day and before the lights go off. Over several days you will see how your tank consumes alk. It will depend your Coral load. If you have a lot of SPS it is easier to see this than if you keep LPS and soft corals. As SPS uptake cal and alk at a steady rate across the day.
Spikes occur from equipment or user error generally.

 

[Leadfooted]

Other than dosing too much or not enough as well as considering what corals consume, what are some examples that caused Alkalinity to swing or spike dramatically, enough to cause damage? Dramatic enough to cause damage. Can dramatic ALK swings be caused in other ways excluding what the corals consume and dosing?

 

[Myka]

Other than dosing too much or not enough as well as considering what corals consume, what are some examples that caused Alkalinity to swing or spike dramatically, enough to cause damage? Dramatic enough to cause damage. Can dramatic ALK swings be caused in other ways excluding what the corals consume and dosing?

1. Reef keeper accidentally doses too much/too little. Forgot to dose, dosed twice. Accidentally mixed fluid too strong, too weak. Etc.
2. Reef keeper accidentally unplugs the doser or the KH doser runs out of fluid.
3. Something dramatic happens in the tank and the corals reduce growth rate (maybe power failure, temp spike, new light burns corals, etc), reef keeper doesn't notice reduced growth rate and KH slowly climbs.
4. Corals are consuming more and more as time goes on and colonies get larger, reef keeper doesn't test KH for a month, and when s/he does, it is very low.

There are a million ways...

 

[Leadfooted]

3. Something dramatic happens in the tank and the corals reduce growth rate (maybe power failure, temp spike, new light burns corals, etc), reef keeper doesn't notice reduced growth rate and KH slowly climbs.

This is a great point

 

[reefwiser]

Right say an event happened in the tank a few corals STN or fish dies. That can effect the uptake of Alk by corals as they will sometimes stop growing for a while. Until things setting back down.

 

[kimros1986]

Alk has a fairly steady decline between doses, perhaps mostly during the day and less at night. The concern with smallish changes is, IMO, not important for all tanks, but may be important for SPS tanks and may be especially important in low nutrient tanks.

Swings can come, for example, by not dosing frequently enough. If you lose 1 dKH per day and dose once a week you will see a substantial swing. Some folks claim that dosing many times per day and keeping alk very stable leads them to observe that their tank seems "better" than if the only dosed once a day.

Old thread but present problem.

Last night I did a software update on my dosetronic. Apperently it lost its calibration and started dosing about 75% more each dose (every second hour). It also lost its connection to my Alkatronic so even though it detected high alk the dosetronic kept dosing every second hour.
To add to this calculation I had a bit of a dip a day earlier due to what I can only assume was increased growth/consumption.
All in all it swang 1,4 Dkh (from 8 as lowest to 9,4 as highest).
I have a sps dominated tank and po4 is at 0,03 and NO3 is at 5 ppm.

What now, should I reach my normal target value at around 8,3-8,7 or let it be up at around 9,4?

Not sure if this swing could affect my sps? Anybody with experience in smaller (?) swings?