Alk Swings

[penguinexdeus]

So I use a Trident to test all the default 4 times a day - midnight,6am,noon,6pm and I dose alk supplements after those tests to correct back to where I want... Naturally as alk is consumed I'm basically testing at the low points before correcting it up causing swings as it's consumed and re-add... So here's what I'm curious about...

Tank is SPS dominate and as my alk usage increases these swings are getting larger... What used to be .1 or .2 dkH swings in each period are getting closer to .5 as things grow... Do I need to "spread out" my dosing more to avoid this? Right now I'm using kalk at night and 2 part during the day with some kalk in between doses during the day and vacuum snuck in twice a day. Kalk is mainly for helping pH. Here's a snapshot photo of what my dosing schedule looks like...

Trying to keep things as stable as possible so any suggestions welcomed as far as timing or dosing...

Alk - targeting 8.2/ 8.3
Calc - targeting about 450, currently 420
Mag - target 1450, currently about 1500
Nitrate about 8, phos about 0.06
PH currently 8.1 to 8.3

 

[KrisReef]

I have a calcium reactor that runs 24/7. If you figure what your typical consumption is in 6 hours, I would think you could dose that amount constantly, (or just slightly less) and then let your Trident set up fill in the gaps?

 

[Garf]

So, is Alkalinity consumption related to light (photosynthesis) or pH? If it’s light, alkalinity swings with calcium reactors can be quite large. Same with kalk, but doubly large if only dosed at night. Unless it’s pH, if steady.

Edit - if it’s light, is that because pH has increased?

 

[Dennis Cartier]

As KrisReef mentioned, dosing a floating baseline and then adjusting from there based on actual tests would help you to moderate the swings.

I run a CaRx and have my Alkatronic test every 6 hours. Based on the most recent alk test, I have my CaRx either slowdown or speedup the effluent flow rate to try to keep as close to 8.6 dKH as possible. I also vary the flow rate over the 24 hour cycle to account for more alk needs during the light cycle and less at night.

A similar approach would help you to keep alk steadier. That being said, most people would say that a .5 dKH swing is nothing to be worried about.

 

[Garf]

As KrisReef mentioned, dosing a floating baseline and then adjusting from there based on actual tests would help you to moderate the swings.

I run a CaRx and have my Alkatronic test every 6 hours. Based on the most recent alk test, I have my CaRx either slowdown or speedup the effluent flow rate to try to keep as close to 8.6 dKH as possible. I also vary the flow rate over the 24 hour cycle to account for more alk needs during the light cycle and less at night.

A similar approach would help you to keep alk steadier. That being said, most people would say that a .5 dKH swing is nothing to be worried about.

Would you surmise that Alk consumption is determined by exterior pH (water) or coral interior pH (photosynthesis within the animal)?

 

[Dennis Cartier]

Would you surmise that Alk consumption is determined by exterior pH (water) or coral interior pH (photosynthesis within the animal)?

I would normally consider alk consumption due to depositing calcium carbonate, so typically tied to photosynthesis. However, higher pH does tend to increase alk consumption which most people attribute to corals having an easier time to depositing calcium carbonate at higher pH's.

 

[Garf]

I would normally consider alk consumption due to depositing calcium carbonate, so typically tied to photosynthesis. However, higher pH does tend to increase alk consumption which most people attribute to corals having an easier time to depositing calcium carbonate at higher pH's.

Wonder why corals would not calcify at night, if appropriate pH thresholds are met?

 

[penguinexdeus]

Just to clarify... I'm not seeing the swings in my testing... My testing is pretty consistent because of consistent testing and dosing times... The swings are based on the consumption I experience in the testing between. So if Im consuming .5 dkH in 6 hours... Should I be dosing every 3 so that the actual swing is .25 vs .5. it's not causing me a problem but let's say later when everything has grown more, what if my consumption becomes 1dkh in 6 hours.... That's a 1dkH swing every 6 hours... I could test and dose at the same times I am now ( just dosing more) for higher consumption and everything looks the same as it does now. I guess this is a philosophical question on how to correctly dose. If I wasn't automatically testing and dosing and just manually testing and adjusting once a day those could be some very extreme daily swings...

 

[Garf]

Just to clarify... I'm not seeing the swings in my testing... My testing is pretty consistent because of consistent testing and dosing times... The swings are based on the consumption I experience in the testing between. So if Im consuming .5 dkH in 6 hours... Should I be dosing every 3 so that the actual swing is .25 vs .5. it's not causing me a problem but let's say later when everything has grown more, what if my consumption becomes 1dkh in 6 hours.... That's a 1dkH swing every 6 hours... I could test and dose at the same times I am now ( just dosing more) for higher consumption and everything looks the same as it does now. I guess this is a philosophical question on how to correctly dose. If I wasn't automatically testing and dosing and just manually testing and adjusting once a day those could be some very extreme daily swings...

If your consuming 1dkh in 6 hours, wow, but I doubt it. Dunno how big your tank is or your Alk consumption but there’s a load of options to replenish. Are you stressing about something that hasn’t happened yet?

 

[penguinexdeus]

If your consuming 1dkh in 6 hours, wow, but I doubt it. Dunno how big your tank is or your Alk consumption but there’s a load of options to replenish. Are you stressing about something that hasn’t happened yet?

Little bit yeah, but it's an exaggerated case. As I moved from daily manual dosing to automated dosing and testing once I got an apex and as i've watched my consumption increase from .1 dkH up to .3 every 6 hours as things started to grow I started to wonder (philosophically of course) if there's a correct way to dose... Or if success is only possible in high consumption tanks with lots of testing and automation to dose continuously in the day. I don't have space for a calcium reactor, and barely managed to fit my kalk dosing in with the two part to help with low ph

 

[Garf]

Little bit yeah, but it's an exaggerated case. As I moved from daily manual dosing to automated dosing and testing once I got an apex and as i've watched my consumption increase from .1 dkH up to .3 every 6 hours as things started to grow I started to wonder (philosophically of course) if there's a correct way to dose... Or if success is only possible in high consumption tanks with lots of testing and automation to dose continuously in the day. I don't have space for a calcium reactor, and barely managed to fit my kalk dosing in with the two part to help with low ph

I had a softy tank for 10 years just on 25% kalk. My current SPS cube is just on kalk, no automation, just paying attention. You’ll be grand

 

[penguinexdeus]

I had a softy tank for 10 years just on 25% kalk. My current SPS cube is just on kalk, no automation, just paying attention. You’ll be grand

Unfortunately I hit my evaporation limit with alk... As I was hoping for the same... But I've had to supplement with 2 part

 

[Pistondog]

I think you are thinking tne right thoughts.
Currently you are measuring and reacting.
We can guess the alk consumption profile during the day tomorrow based on todays measurements and todays dosing.
Can you add more before peak consumption to minimize swings?
Are there alk swings daily in the ocean?

 

[Randy Holmes-Farley Verified Community Expert]

Wonder why corals would not calcify at night, if appropriate pH thresholds are met?

I think we do not have the data to disentangle the pH and direct light effects.

I'd still waiting for someone to have a reverse pH swing due to a huge reverse lit refugium, and then track alk consumption over 24 h.

 

[Randy Holmes-Farley Verified Community Expert]

Are there alk swings daily in the ocean?

Alk does not generally change over 24 h in the ocean.

 

[Pistondog]

Little bit yeah, but it's an exaggerated case. As I moved from daily manual dosing to automated dosing and testing once I got an apex and as i've watched my consumption increase from .1 dkH up to .3 every 6 hours as things started to grow I started to wonder (philosophically of course) if there's a correct way to dose... Or if success is only possible in high consumption tanks with lots of testing and automation to dose continuously in the day. I don't have space for a calcium reactor, and barely managed to fit my kalk dosing in with the two part to help with low ph

As Randy confirmed, the ocean does not have significant alk swings over 24 hours.
We always say for success keep parameters steady. Shouldnt this include alk levels?
If you know how much the tank consumes, cheating the dose higher just prior and during peak consumption might minimize the daily swing.

 

[epicfatigue]

I think we do not have the data to disentangle the pH and direct light effects.

I'd still waiting for someone to have a reverse pH swing due to a huge reverse lit refugium, and then track alk consumption over 24 h.

@Randy Holmes-Farley I'm about to be doing this I have a design I am about to be implementing in the comming months. Happy for you to provide some input, I have designed my own pH monitor and alkalinity monitor to capture the data for sampling. I'm also going to be designing a bubble tower for the refugium to enrich it with sufficient oxygen. I know CO2 is required for the cheato but I found that even with the skimmer alone using outside air free co2 was still lurking, the tower may not be required with a large refugium but if I am unable to keep up with nutrients this may be used to in conjunction.


As you can see from the table below please not alkalinity dosed is 0 because I am manually doing it after data collected.

The purple dot was my original curve, which was very stable but a large dip when pH approached 8.2.

Green was when I increased my calcium reactor but this decreased the peak but caused alkalinity to rise during the night.

Red is where we are now where I have turned the calcium reactor off over night and have increased its amount dosed during daylight hours (currently trailing)

This should keep my alkalinity more stable but will not cater for my PH which is why I am going to be installing a basement sump with direct access to outside air, currently my skimmer sucks outside air which improved my PH so this seems the next logical step.

I would be adding a refugium that will be the same size as the display that will have a bubble tower in it, this will be a cube half in half out of the water to avoid salt spray and evaporation. It will be powered by a very large air pump which will flood the cube with outside air and then flow into the oversized refugium which will be powered by some commerical grow lights. The intent of this setup is to match the photosynthesis of the display and keep the pH stable, my issue is going to be keeping the nutrients up in the tank, as I have conducted a small scale experiment in the past and cheato consumes much my nutrients then a display.