Help me find alkalinity stability

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Tank is 4.5 months old, and I have had a fun time automating and getting my nutrients and parameters stable...with the exception of Alkalinity (for now).

Tank/Sump: RS Reefer 525xl with Trigger 34" Platinum Sump ~ 110gal volume
Sand: 3" DSB 150lbs started dry
Rock: 150lbs of clean dry rock
Lighting: 1 x Kessil AP9x and 2 x Kessil A360x; 10am to 10pm with slow ramp up/down ~ w/ 6hr of full lighting
Mechanical Filtration: Roller Mat
Refugium: Chaeto, Calerpa Prolifera, and GHA; 10pm to 10am Kessil h160 Tuna Flora
Media: MarinePure blocks; Chemi-pure Blue
Skimmer: Aeraqua Duo with recirculating CO2 Scrubber (mostly used to maintain pH)
Return pump: Vectra L1
Powerheads: 2 x Reefwave 45
Heater/Chiller: Teco TK-1000
AWC: 1% incremental daily water change with TMP
Dosing: 1dKH daily of Kalkwasser @ 3ml/min; 16ml or Reef Energy AB+; ChaetoGro (Occasionally)

Tank Parameters:
Temp: 76.5 - 77.5
Salinity: 1.025ish
Ca: 450ish
Mg: 1425ish
NO3: >1ppm (bounces around based on feeding)
PO4: >.01ppm (bounces around based on feeding)

Alkalinity:
Presentation1.png


This just seems to be a little all over the place and I have verified my GHL reading with my Hannah Alkalinity checker many times and they are always very close.

With my previous tank, I was able to automate dosing to get very steady alkalinity (before I changed salts to Neomarine - not sure why I couldn't get back to a steady-state).

I want to get back to automating this...but I'm not sure what's up here.

Also, note that I don't have too much coral in the tank. Mostly just small frags with the majority being softies. I don't seem to have coralline algae yet either.

With 1 dKH kalk daily dosing I was either expecting Alk to rise or fall over time, not this meandering.

Any insight or advice?
 
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All I would say is that this level of stability would make me happy. Alkalinity consumption changes throughout the day as well as over time in a maturing reef. I always shoot for no more than a 1DKH change in a day when dialing in dosing and you are well within that. You could try only dosing alk during the day when it is consumed but if it were me I wouldn't worry.
 
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All I would say is that this level of stability would make me happy. Alkalinity consumption changes throughout the day as well as over time in a maturing reef. I always shoot for no more than a 1DKH change in a day when dialing in dosing and you are well within that. You could try only dosing alk during the day when it is consumed but if it were me I wouldn't worry.
With my old tank and GHL, I was really able to dial it in like within +/- 0.2. I would measure 6 times a day and adjust dosing.
 

Greg P

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With my old tank and GHL, I was really able to dial it in like within +/- 0.2. I would measure 6 times a day and adjust dosing.
Before I found my daily usage I tested once only per day, and at the same time of day.
Your graph is showing swings within reason.
With dosing, if you can test once daily and have the same results day after day you're doing fine.
 
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I continue to monitor with 1dKH kalk dosing:

Screenshot_20210408-083057_GHL Connect.jpg


It waa looking like a slow additional consumption of 0.1dKH per day, but last 4 measurements have shown a steeper decline.

I'll continue to monitor, as the last time this happened it swung back up.

If the trend continues down for the next couple of days, I'll consider dosing additional supplements.

I'm leaning to using AFR.
 
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So I found where my alkalinity is going...

Sand is clumping.

I've dialed down my pH by 0.05.

I also started dosing AFR at 7ml per day (0.1dkh) ...ended up getting a unexpected uptick in Alk and consequently stopped dosing.

@Randy Holmes-Farley Is clumping sand an actual problem? I'm just breaking it up with a pointy object.
 
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Quick update here for those that may be following.

1. I was seeing a very steady 0.1 decline in Alk
2. My Kalk was at its dosing limit ~1dKH
3. I theorise my Alk demand is mostly abiotic precipitation (clumping sand)
4. Decided to use AFR to at 0.1 Alk
5. Had very funky Alk results from AFR. See:
6. Trimmed my pH from 8.35 to 8.30 to reduce abiotic demand
7. Cut my Kalk dosing to 0.9dKH
8. Looks like 2 doses of 1ml AFR a day is working to stabilize my Alk

So Im still pondering how to really lock in Alk stability. Since AFR Alk effects can be delayed, this makes automating it difficult.

I may further back-off kalk dosing and play with AFR dosing to see the impacts and ability to control Alk.
 

Randy Holmes-Farley

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Shankpa1

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Tank is 4.5 months old, and I have had a fun time automating and getting my nutrients and parameters stable...with the exception of Alkalinity (for now).

Tank/Sump: RS Reefer 525xl with Trigger 34" Platinum Sump ~ 110gal volume
Sand: 3" DSB 150lbs started dry
Rock: 150lbs of clean dry rock
Lighting: 1 x Kessil AP9x and 2 x Kessil A360x; 10am to 10pm with slow ramp up/down ~ w/ 6hr of full lighting
Mechanical Filtration: Roller Mat
Refugium: Chaeto, Calerpa Prolifera, and GHA; 10pm to 10am Kessil h160 Tuna Flora
Media: MarinePure blocks; Chemi-pure Blue
Skimmer: Aeraqua Duo with recirculating CO2 Scrubber (mostly used to maintain pH)
Return pump: Vectra L1
Powerheads: 2 x Reefwave 45
Heater/Chiller: Teco TK-1000
AWC: 1% incremental daily water change with TMP
Dosing: 1dKH daily of Kalkwasser @ 3ml/min; 16ml or Reef Energy AB+; ChaetoGro (Occasionally)

Tank Parameters:
Temp: 76.5 - 77.5
Salinity: 1.025ish
Ca: 450ish
Mg: 1425ish
NO3: >1ppm (bounces around based on feeding)
PO4: >.01ppm (bounces around based on feeding)

Alkalinity:
Presentation1.png


This just seems to be a little all over the place and I have verified my GHL reading with my Hannah Alkalinity checker many times and they are always very close.

With my previous tank, I was able to automate dosing to get very steady alkalinity (before I changed salts to Neomarine - not sure why I couldn't get back to a steady-state).

I want to get back to automating this...but I'm not sure what's up here.

Also, note that I don't have too much coral in the tank. Mostly just small frags with the majority being softies. I don't seem to have coralline algae yet either.

With 1 dKH kalk daily dosing I was either expecting Alk to rise or fall over time, not this meandering.

Any insight or advice?
bump
 
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Just to be clear:
1. I had a downward trend of 0.1 Alk per day
2. I was at my Kalk limit
3. I added 0.1 dKH of AFR (7ml)
4. Alk unexpectedly shot up
5. Stopped AFR and backed off Kalk by 0.1dKH until levels came back down
6. Restarted AFR at 1ml
7. Slowly increased AFR
8. I'm up to 8ml AFR
9. Looks like tank may be stabilizing where I think it should be based on target pH/Alk/CO2 levels
 
AS

Randy Holmes-Farley

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For those following along...slow increase of AFR resulted in:

Presentation2 (2).png


It seems that it may take time for the bacteria that metabolize AFR to kick into gear...feels like carbon dosing. Start slow and build up.

Nice info.

What are the time scales along the bottom? What is the range of alk in the y-axis?

The dose values are per day?
 
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Nice info.

What are the time scales along the bottom? What is the range of alk in the y-axis?

The dose values are per day?

I can see if I can make it more readable.

Bottom time scale is days. I typically have 4 measurements per day unless I'm tracking impacts of changes. There is 1 months worth of data at least measured at 12am, 6am, 12pm 6pm every day.

Alk scale is 0.2 and has high of 8.6dKH and low of 7dKH.

Doses are per day and spread out evenly. So right now 2ml 4x a day.
 
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I can see if I can make it more readable.

Bottom time scale is days. I typically have 4 measurements per day unless I'm tracking impacts of changes. There is 1 months worth of data at least measured at 12am, 6am, 12pm 6pm every day.

Alk scale is 0.2 and has high of 8.6dKH and low of 7dKH.

Doses are per day and spread out evenly. So right now 2ml 4x a day.
Screenshot 2021-05-05 183800.jpg
Probably not any more clear...
 
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Again to be clear, I am now dosing 8ml per day...which is what I had basically calculated I needed on top of my Kalkwasser. Alk has been stable for the last 2 days going between 7.5 and 7.6. If it maintains this stability I'm very happy...
 
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So stability still eludes me. I'm not sure that AFR can be used to lock in Alk. I'm ordering TM Balling products (too lazy for DIY). The plan is as follows:

1. Continue max Kalk
2. Continue AFR
3. Add Balling for daily adjustments

I'm hoping that at some point AFR metabolizes quickly in tank and Balling gets discarded.

So here's how it will work:
1. Alk setpoint will be 7.6
2. Kalk dosing 0.8dKH (current limit)
3. AFR dosing 0.2dKH
4. GHL monitoring Alk with readings below setpoint, GHL will immediately dose to setpoint and up AFR.
5. With Alk above setpoint, GHL will reduce AFR.

As I'm mostly seeing increased Alk demand, this should really stabilize my Alk.
 
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