What causes alk fluctuations through the day and how do I stabilize?

[Nano sapiens]

Why did you decide to wait a few years?

Slowly built the mixed reef, most sensitive species last.

If your Acro(s) is/are successful you'll have to deal with a fast growing and often aggressive coral. Every few years I grow one just for fun, but then move it on again when it gets too much to deal with (14 year old system).

 

[livinlifeinBKK]

Slowly built the mixed reef, most sensitive species last.

I'm not in any big hurry to flood my tank with acros like some reefers I've come across, just here in BKK for certain reasons there isn't nearly the variety of corals available as there are in a lot of other places and for whatever reason a lot of the sellers primarily stock a wide variety of acros like tenuis so when looking to add some color to the reef they're the most commonly available so before I start having alk and other parameter swings and have to invest in a doser I was thinking about adding one of them

 

[Nano sapiens]

I'm not in any big hurry to flood my tank with acros like some reefers I've come across, just here in BKK for certain reasons there isn't nearly the variety of corals available as there are in a lot of other places and for whatever reason a lot of the sellers primarily stock a wide variety of acros like tenuis so when looking to add some color to the reef they're the most commonly available so before I start having alk and other parameter swings and have to invest in a doser I was thinking about adding one of them

If your Acro takes off you'll need to replace Alk and Ca in a hurry! It's amazing how fast an Acro's metabolism is when conditions are right.

I add a clear saturated Kalkwasser and RO solution to my gravity fed ATOs at a predetermined ratio. A DIY drip doser is another option if the tank's evaporation rate swings too much for dosing via an ATO.

Spending big bucks on a commercial doser for a small nano is really not necessary, but certainly your choice.

 

[livinlifeinBKK]

I add a clear saturated Kalkwasser and RO solution to my gravity fed ATOs at a predetermined ratio. A DIY drip doser is another option if the tank's evaporation rate swings too much for dosing via an ATO.

Spending big bucks on a commercial doser for a small nano is really not necessary, but certainly your choice.

Your way sounds better!

 

[Randy Holmes-Farley Verified Community Expert]

It's normal for your alk to change through the day

Why do you think that?

Most processes in a reef tank cause an alk decline, and if you are not dosing, it would be unusual to get any significant rises in alk on a daily basis.

 

[Randy Holmes-Farley Verified Community Expert]

A rise in pH and alk during the lighting period is inevitable when photosynthetic organisms (like coral) uptake calcium carbonate. One

Why would the alk rise from an organism taking up calcium carbonate? Did you mean an alk decline?

 

[Randy Holmes-Farley Verified Community Expert]

Like I said, with the test kit I use just one extra drop of titrant (~.02 ml) changes the reading by .3 or .4 dkh

My expectation that what you are detecting as alk variability is really testing variability.

 

[Dennis Cartier]

I woke up thinking about this thread, lol.

He is running a nano. Could it be his ATO is allowing a big enough swing in salinity to show up in his alkalinity? I had the same issue with a stock tank sump where the surface area of the sump is so large, compared to the tank, that a 1/2" drop or rise in water level causes a detectable rise or fall in alkalinity.

Perhaps what he is seeing is the cycling of his ATO depending on timing and evaporation.

 

[livinlifeinBKK]

My expectation that what you are detecting as alk variability is really testing variability.

I think you're right...the top line on the syringe to fill the titrant to is worn off so that adds a little guess work to where I should fill the syringe with titrant to and one extra drop of titrant gives a difference of .3-.4 dkh...also I checked out of curiosity and found the test kit expired in March (I don't know if 1 month past expiration would make a difference though

 

[livinlifeinBKK]

I woke up thinking about this thread, lol.

He is running a nano. Could it be his ATO is allowing a big enough swing in salinity to show up in his alkalinity? I had the same issue with a stock tank sump where the surface area of the sump is so large, compared to the tank, that a 1/2" drop or rise in water level causes a detectable rise or fall in alkalinity.

Perhaps what he is seeing is the cycling of his ATO depending on timing and evaporation.

That also sounds plausible...I think I'm going to get a new test kit this weekend since I just found out today that the kit I've been using expired in March, I'm thinking a Red Sea alk pro kit maybe even though it's a little more expensive and I'll continue to keep a log of my test results

 

[Randy Holmes-Farley Verified Community Expert]

I woke up thinking about this thread, lol.

He is running a nano. Could it be his ATO is allowing a big enough swing in salinity to show up in his alkalinity? I had the same issue with a stock tank sump where the surface area of the sump is so large, compared to the tank, that a 1/2" drop or rise in water level causes a detectable rise or fall in alkalinity.

Perhaps what he is seeing is the cycling of his ATO depending on timing and evaporation.

That is certainly possible.

 

[Nano sapiens]

Why would the alk rise from an organism taking up calcium carbonate? Did you mean an alk decline?

Yes, I meant '...a rise in alk usage', but I'm not able to edit the post.

I can see where writting 'an alk decline' is a better way to phrase this.

 

[livinlifeinBKK]

That is certainly possible.

If this is the case, is there anything I can or should do about it?

 

[Randy Holmes-Farley Verified Community Expert]

If this is the case, is there anything I can or should do about it?

Probably not.

Are you measuring salinity?

 

[Biff0rz]

Why do you think that?

Most processes in a reef tank cause an alk decline, and if you are not dosing, it would be unusual to get any significant rises in alk on a daily basis.

I mean, I've watched it happen consistently with my alkatronic testing hourly - and it wasn't due to testing fluctuations or errors. I agree most processes will consume it. But even with consistent dosing you'll notice slight swings up and down during the photoperiod and non-photoperiod. Consumption isn't consistent through the day so there is variation thus swings. Now those swings generally aren't as wide as the op's issue but they are there. Attached is the past few tests witb my alkatronic, notice the small variations? I dose with a calcium reactor at a consistent rate. Without the PH swings alk would remain more flat.

 

[livinlifeinBKK]

Probably not.

Are you measuring salinity?

Yeah, I had a less expensive refractometer that I had calibrated by a LFS...I hadn't recalibrated it for a long time so a few months ago I got an electronic salinity tester that was supposed to come precalibrated...I will admit that it wouldn't surprise me if it was slightly off but I do have an Ice Cap ATO so salinity should be constant in the tank (only exception would be that if my refractometer did happen to be off my weekly water changes could slightly vary in salinity). I do always test for salinity with my electronic tester when mixing water and I do test now and then in my tank despite having the ATO

 

[Randy Holmes-Farley Verified Community Expert]

I mean, I've watched it happen consistently with my alkatronic testing hourly - and it wasn't due to testing fluctuations or errors. I agree most processes will consume it. But even with consistent dosing you'll notice slight swings up and down during the photoperiod and non-photoperiod. Consumption isn't consistent through the day so there is variation thus swings. Now those swings generally aren't as wide as the op's issue but they are there. Attached is the past few tests witb my alkatronic, notice the small variations? I dose with a calcium reactor at a consistent rate. Without the PH swings alk would remain more flat.

Sure, I'm just stating that alk itself doesn't fluctuate in the absence of dosing. Demand is not exactly steady all the time, with much more during the daylight hours) and if you dose steady, alk will fluctuate.

 

[Randy Holmes-Farley Verified Community Expert]

Yeah, I had a less expensive refractometer that I had calibrated by a LFS...I hadn't recalibrated it for a long time so a few months ago I got an electronic salinity tester that was supposed to come precalibrated...I will admit that it wouldn't surprise me if it was slightly off but I do have an Ice Cap ATO so salinity should be constant in the tank (only exception would be that if my refractometer did happen to be off my weekly water changes could slightly vary in salinity). I do always test for salinity with my electronic tester when mixing water and I do test now and then in my tank despite having the ATO

If the tank volume declines by 2% (roughly 1/2 inch volume level on a 24 inch deep tank), then salinity and alk will rise by 2%, or say from 8.00 to 8.16 dKH.