Alkalinity Precipitation?

kyleorso

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Hello. I have researched some info on the topic but hoping to be pointed in the right direction. What are possible causes or things I can check / verify to find why my Alk started precipitating out?

I recently had a Alk drop and I cant recover no matter how much I dose. I have about 100 gallons water volume in my system. I have a Apex and Trident. I dose BRS 2 part using the Apex DOS. My tank has been very stable keeping a 9.0 dkh, 450 calcium, and 1400 mag. PH 8.35 during the day and 8.25 at night when lights are out. Salinity is 34.7 on hannah salinity checker that i verify with refractometer every now and then. For the last 6 months it has taken 16-20ml of BRS soda ash alkalinity mix every day to maintain 9.0. It has taken 10ml of BRS calcium along with 20% weekly water changes to keep 450 cal. I use Tropic Marin Pro salt.

Everything was fine and stable like clock work until about a week ago when my Alk dropped overnight to about 7.9. I dosed some extra to start bringing it up and it didn't really move. Eventually with big doses its up to about 8.5 but it has went from taking 20ml of alk per day to 200ml and i'm losing ground. So i finally figured out that its likely precipitating. I did add a large maxima clam a few days before the issue started. I thought that might be the issue at the beginning but I don't think she is taking 200ml of alk per day.

I have calibrated the Trident and verified the reading with manual test. Hannah checker for Alk and Salifert & Rea Sea both for Calc. On calc the test all read differently but are in the ball park. None of them are maxed out at over 500.

Why would it start precipitating suddenly when it hadn't been and what process can I do to figure out why its doing it and how to correct it? Thanks.
 
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Acskippy

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Hello. I have researched some info on the topic but hoping to be pointed in the right direction. What are possible causes or things I can check / verify to find why my Alk started precipitating out?

I recently had a Alk drop and I cant recover no matter how much I dose. I have about 100 gallons water volume in my system. I have a Apex and Trident. I dose BRS 2 part using the Apex DOS. My tank has been very stable keeping a 9.0 dkh, 450 calcium, and 1400 mag. PH 8.35 during the day and 8.25 at night when lights are out. Salinity is 34.7 on hannah salinity checker that i verify with refractometer every now and then. For the last 6 months it has taken 16-20ml of BRS soda ash alkalinity mix every day to maintain 9.0. It has taken 10ml of BRS calcium along with 20% weekly water changes to keep 450 cal. I use Tropic Marin Pro salt.

Everything was fine and stable like clock work until about a week ago when my Alk dropped overnight to about 7.9. I dosed some extra to start bringing it up and it didn't really move. Eventually with big doses its up to about 8.5 but it has went from taking 20ml of alk per day to 200ml and i'm losing ground. So i finally figured out that its likely precipitating. I did add a large maxima clam a few days before the issue started. I thought that might be the issue at the beginning but I don't think she is taking 200ml of alk per day.

I have calibrated the Trident and verified the reading with manual test. Hannah checker for Alk and Salifert & Rea Sea both for Calc. On calc the test all read differently but are in the ball park. None of them are maxed out at over 500.

Why would it start precipitating suddenly when it hadn't been and what process can I do to figure out why its doing it and how to correct it? Thanks.
Trident calibrations always seem to swing my readings pretty significantly... i use trident, but everytime i calibrate it i use 3 other test methods and get an average... the readings i get on the trident i just use from then on as an indicator of drastic swings NOT for the “reading” itself. As long as the readings are staying stable on my trident i use same dosing regimen... i would not use the tridents “numbers” as end all be all, just watch for severe swings between calibrations... if you want to see what your alk precipitating out would look like mix part 1 and 2 together in a seperate disposable cup... doubt its an extreme alk swing, probably trident calibration, or addition/removal of live stock or other equip/reactors... if the tank looks good, keep on doing what you were doing, as changing anything (especially dosing) could have nasty effects on ur livestock. How long have you been running your trident out of curiosity? Also do you use the calibration fluid immediately after opening?
 

Acskippy

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Hello. I have researched some info on the topic but hoping to be pointed in the right direction. What are possible causes or things I can check / verify to find why my Alk started precipitating out?

I recently had a Alk drop and I cant recover no matter how much I dose. I have about 100 gallons water volume in my system. I have a Apex and Trident. I dose BRS 2 part using the Apex DOS. My tank has been very stable keeping a 9.0 dkh, 450 calcium, and 1400 mag. PH 8.35 during the day and 8.25 at night when lights are out. Salinity is 34.7 on hannah salinity checker that i verify with refractometer every now and then. For the last 6 months it has taken 16-20ml of BRS soda ash alkalinity mix every day to maintain 9.0. It has taken 10ml of BRS calcium along with 20% weekly water changes to keep 450 cal. I use Tropic Marin Pro salt.

Everything was fine and stable like clock work until about a week ago when my Alk dropped overnight to about 7.9. I dosed some extra to start bringing it up and it didn't really move. Eventually with big doses its up to about 8.5 but it has went from taking 20ml of alk per day to 200ml and i'm losing ground. So i finally figured out that its likely precipitating. I did add a large maxima clam a few days before the issue started. I thought that might be the issue at the beginning but I don't think she is taking 200ml of alk per day.

I have calibrated the Trident and verified the reading with manual test. Hannah checker for Alk and Salifert & Rea Sea both for Calc. On calc the test all read differently but are in the ball park. None of them are maxed out at over 500.

Why would it start precipitating suddenly when it hadn't been and what process can I do to figure out why its doing it and how to correct it? Thanks.
200 ml is ALOT OF ALK! I run mixed 250 gallon and i dose 60ml 1 & 2
 
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I have been running trident for about 6 months. My trident doesnt have many swings unless the reagent is low. For alk it is always within .1 of my hanna checker depending on reagent batch. Most of the time I get the same reading. Calcium is the biggest issue for me as far as swings on my trident. But I also get a wide reading between my 2 manual test kits. As stated I have verified all the readings many multiples of times with test other than trident.

I tested mag yesterday with red sea kit and its inline with my trident reading of 1400.

Tank is 75 gallon. Minus rock volume and add sump I have 100 gallon water volume. I have mostly zoas and a few lps. No SPS. One large maxima clam. Lots of coraline algee.

Nothing is wrong with it sitting at 8 dkh in principle but the issue is now its already below 8 dkh today. Tank uses about .2 dkh per day which my 20 ml of alk would replace normally. Now its dropping each day so its not going to sit at 8 stable.
 
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Shaun_in_Cali

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I have been running trident for about 6 months. My trident doesnt have many swings unless the reagent is low. For alk it is always within .1 of my hanna checker depending on reagent batch. Most of the time I get the same reading. Calcium is the biggest issue for me as far as swings on my trident. But I also get a wide reading between my 2 manual test kits. As stated I have verified all the readings many multiples of times with test other than trident.

I tested mag yesterday with red sea kit and its inline with my trident reading of 1400.

Tank is 75 gallon. Minus rock volume and add sump I have 100 gallon water volume. I have mostly zoas and a few lps. No SPS. One large maxima clam. Lots of coraline algee.

Nothing is wrong with it sitting at 8 dkh in principle but the issue is now its already below 8 dkh today. Tank uses about .2 dkh per day which my 20 ml of alk would replace normally. Now its dropping each day so its not going to sit at 8 stable.
What I’m suggesting is rather than throwing in 200ml trying to raise it, would it sit at 8 if you just dose 20ml/day?
 
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Randy Holmes-Farley

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The ways to reduce precipitation are to stop dosing for a while to let the fresh CaCO3 surfaces get clogged with other ions.

Then when you restart after a few days, keep alk at 7 dKH, keep pH low (dose bicarbonate for alk, stop any CO2 scrubbing), keep magnesium, organics and phosphate high, keep calcium normal to low.
 
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kyleorso

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What I’m suggesting is rather than throwing in 200ml trying to raise it, would it sit at 8 if you just dose 20ml/day?
right at about 24 hours ago I switched the DOS back to 20ml per day. I was afraid things would correct themselfw and I would nuke the tank at 200ml. Its still dropping as if im not dosing. At 200ml it would hold its own or drop maybe .2 over 2 days instead of 1 day. But it basically like im not dosing regardless of the volume I put in. I also ran a 20 ml pump profile I have setup on a feed button for one time corrections. I ran it into a graduated cylinder and it put out exactly 20ml. I was checking to see the DOS was working right and the volume was actually going into the tank.
 
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kyleorso

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The ways to reduce precipitation are to stop dosing for a while to let the fresh CaCO3 surfaces get clogged with other ions.

Then when you restart after a few days, keep alk at 7 dKH, keep pH low (dose bicarbonate for alk, stop any CO2 scrubbing), keep magnesium, organics and phosphate high, keep calcium normal to low.

Thanks Randy! After this reset and I keep the parameters as described, is there a certain amount of time before I can start raising them?
 

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Thanks Randy! After this reset and I keep the parameters as described, is there a certain amount of time before I can start raising them?

I usually recommend waiting a few days (3?) before restarting dosing.. :)
 
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The ways to reduce precipitation are to stop dosing for a while to let the fresh CaCO3 surfaces get clogged with other ions.

Then when you restart after a few days, keep alk at 7 dKH, keep pH low (dose bicarbonate for alk, stop any CO2 scrubbing), keep magnesium, organics and phosphate high, keep calcium normal to low.
Hi Randy how do you tackle the issue of Alk drop when you stop dosing for 3 days due to precipitation?
 

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Hi Randy how do you tackle the issue of Alk drop when you stop dosing for 3 days due to precipitation?

You don't. You let it drop.
 

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Alk at 8.0 should not precipitate.. it's so so so so far away from near saturation.

What?

Normal seawater at pH 8.1 and 6.5 dKH and 420 ppm calcium is well above saturation for aragonite and calcite, and will precipitate given fresh calcium carbonate surfaces.

Any levels above that drive precipitation even faster. pH is an especially big driver.
 
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What?

Normal seawater at pH 8.1 and 6.5 dKH and 420 ppm calcium is well above saturation for aragonite and calcite, and will precipitate given fresh calcium carbonate surfaces.

Any levels above that drive precipitation even faster. pH is an especially big driver.
What???

So I can't run my tank at DKH of 12 - the entire thing will precipitate?
 

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What???

So I can't run my tank at DKH of 12 - the entire thing will precipitate?

Of course not. But it is still supersaturated and if you provide seed crystals of calcium carbonate in some way, it will.


Kinetics of CaCO3 homogeneous precipitation in seawater

The stable supersaturation of CaCO3 in surface
seawater of many oceanic areas ranges from 2-3 to
6-7 times. Nevertheless the spontaneous precipita-
tion of CaCO3 is very retarded due to different
inhibitors: dissolved organic matter [1,3], phos-
phates [3] magnesium [2,4].
 

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Of course not. But it is still supersaturated and if you provide seed crystals of calcium carbonate in some way, it will.


Kinetics of CaCO3 homogeneous precipitation in seawater

The stable supersaturation of CaCO3 in surface
seawater of many oceanic areas ranges from 2-3 to
6-7 times. Nevertheless the spontaneous precipita-
tion of CaCO3 is very retarded due to different
inhibitors: dissolved organic matter [1,3], phos-
phates [3] magnesium [2,4].
Then there is no harm in continuing dosing Alkalinity? Eventually all calcium carbonate molecules will be bound and precipitation would stop?
 

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Then there is no harm in continuing dosing Alkalinity? Eventually all calcium carbonate molecules will be bound and precipitation would stop?

If there is ongoing precipitation (e.g., sand hardening) then it can be very hard to maintain alkalinity even with large doses (say, 4 dKH per day) because the fresh calcium carbonate surfaces do not have time to get "poisoned" with the things mentioned above before more fresh CaCO3 precipitates on it.

That's the reason for the reduced dosing for a while: to let organics, phosphate, and magnesium clog up the surfaces.
 

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