Need Help with Falling Alkalinity

[AKL1950]

I have been trying to raise my alkalinity (and PH) over the past month and I need some guidance on best options to get it up to the 8.3-8.5 range. The salt I use is Reef Crystals and it mixes up at around 11.0 Alk. I change 3 gallons a day. Total water volume in the system is about 190 gallons. My PH was running low as well, range 7.8 to 7.95, so I got a CO2 scrubber and now it runs from 8.15 to 8.3. I have added a good complement of SPS and LPS over the last few months. Alkalinity is dropping about .3 per week. Currently at 7.6. I dose Brightwell part A Alkalinity 5ml per day. Not dosing Ca or Mag yet. The system is about 10 months along and I’m starting to see good increased growth of coraline algae and encrusting of the SPS corals on the rock around their posts.

Testing is done using Trident with Salifert and Hanna backups. Current parameters are:

Salinity. 34.8
Temp. 80
PH. 8.23
NO3. 11.1
PO4. 0.04
Alk. 7.6
Cal. 500
Mag. 1625

Since my Cal and Mag are pretty stable, I’m just trying to get Alkalitity up a bit. Would it be better to increase my Part A dosing or use some Baking Soda or Sodium Carbonate to get it up to the 8.3-8.5 range?

Jetson

 

[homer1475]

Whats wrong with 7.6?

Just use a calculator to get your dosage to raise, then dose in one shot. Don't go over 1dkh in one shot though as it can stress corals.

Reef Chemistry Calculator

 

[SPS2020]

I have been trying to raise my alkalinity (and PH) over the past month and I need some guidance on best options to get it up to the 8.3-8.5 range. The salt I use is Reef Crystals and it mixes up at around 11.0 Alk. I change 3 gallons a day. Total water volume in the system is about 190 gallons. My PH was running low as well, range 7.8 to 7.95, so I got a CO2 scrubber and now it runs from 8.15 to 8.3. I have added a good complement of SPS and LPS over the last few months. Alkalinity is dropping about .3 per week. Currently at 7.6. I dose Brightwell part A Alkalinity 5ml per day. Not dosing Ca or Mag yet. The system is about 10 months along and I’m starting to see good increased growth of coraline algae and encrusting of the SPS corals on the rock around their posts.

Testing is done using Trident with Salifert and Hanna backups. Current parameters are:

Salinity. 34.8
Temp. 80
PH. 8.23
NO3. 11.1
PO4. 0.04
Alk. 7.6
Cal. 500
Mag. 1625

Since my Cal and Mag are pretty stable, I’m just trying to get Alkalitity up a bit. Would it be better to increase my Part A dosing or use some Baking Soda or Sodium Carbonate to get it up to the 8.3-8.5 range?

Jetson

Either Soda Ash or Sodium Bicarbonate with raise Alk. Soda Ash will increase pH more.

 

[Randy Holmes-Farley Verified Community Expert]

Alk of 8.3 to 8.5 dKH is a rather narrow and specific range. Why elect that? I just want to be sure you are not confusing it with a pH recommendation.

 

[nereefpat]

So alk is dropping 0.3 dKH per week, and you are dosing 5 mLs per day in a 190 gallon system.

It sounds like you just need to dose a little more.

Using this calculator: https://reef.diesyst.com/chemcalc/chemcalc.html
5 mLs of Brightwell liquid in 190 gallons is only something like 0.1 dKH.

 

[AKL1950]

Alk of 8.3 to 8.5 dKH is a rather narrow and specific range. Why elect that? I just want to be sure you are not confusing it with a pH recommendation.

I’m still new at this Randy and still learning. I did learn on the PH we were discussing on another thread. CO2 scrbber did the trick. I thought that range was the alkalinity range one would like to see and stable at that range. Everything seems to be growing well at the high 7s, but since alkalinity is dropping weekly I assume that the increase in coral growth is causing the alkalinity to start dropping. I’m looking to move it back up to that range (okay, between 8.0 and 8.5), and try to keep it stable there (Now that I have the PH where I want it). If I’m trying to be too exact, that would be a good learning point as well.

So alk is dropping 0.3 dKH per week, and you are dosing 5 mLs per day in a 190 gallon system.

It sounds like you just need to dose a little more.

Using this calculator: https://reef.diesyst.com/chemcalc/chemcalc.html
5 mLs of Brightwell liquid in 190 gallons is only something like 0.1 dKH.

Sounds like I need to at least double that to 10 ml a day and see if the dropping stops. If so, then start increasing a little more to get back up to the mid 8 level. I assume the more my corals grow the more I will have to dose, constantly tweeting the amount. Correct?

Side question is I don’t see any significant drop in Ca or Mag. They are both fairly stable. Shouldn’t I start seeing a drop in them as well since I’m seeing a good increase in coral growth?

Jetson

 

[nereefpat]

Sounds like I need to at least double that to 10 ml a day and see if the dropping stops. If so, then start increasing a little more to get back up to the mid 8 level.

If you are dosing a tiny amount, and the alk is dropping, then yes I would increase the dose. Going to 10 mLs a day should be fine. It can be a bit of a 'guess and check' type of thing.

I assume the more my corals grow the more I will have to dose, constantly tweeting the amount. Correct?

To some extent yes. Early on, the tank will consume less alk. As corals and coralline algae start to grow, you'll need to dose more. At some point the increase does seem to level off.

Side question is I don’t see any significant drop in Ca or Mag. They are both fairly stable. Shouldn’t I start seeing a drop in them as well since I’m seeing a good increase in coral growth?

Jetson

If what I'm seeing in the calculator is correct, 5 mLs isn't much alk consumption. Somewhere in the order of 0.1 dKH per day. For every 1 dKH of alk used, corals use about 7 ppm Calcium. Magnesium consumption is around 1/10th the consumption of Ca. So the theoretical use of Ca in your system is around 1 ppm per day, and Mg is in the order of .1 per day or less. Your test kits for Ca and Mg will be about +/- 20 ppm and can't pick that up.

 

[AKL1950]

If you are dosing a tiny amount, and the alk is dropping, then yes I would increase the dose. Going to 10 mLs a day should be fine. It can be a bit of a 'guess and check' type of thing.

To some extent yes. Early on, the tank will consume less alk. As corals and coralline algae start to grow, you'll need to dose more. At some point the increase does seem to level off.

If what I'm seeing in the calculator is correct, 5 mLs isn't much alk consumption. Somewhere in the order of 0.1 dKH per day. For every 1 dKH of alk used, corals use about 7 ppm Calcium. Magnesium consumption is around 1/10th the consumption of Ca. So the theoretical use of Ca in your system is around 1 ppm per day, and Mg is in the order of .1 per day or less. Your test kits for Ca and Mg will be about +/- 20 ppm and can't pick that up.

Thanks! That all makes sense. I’m weird. I love math and chemistry almost as much as I like watching these things grow. I will make the change on dosing the alkalinity and see how it does for a week or so, then readjust from there. If the corals grow faster, that will be even more fun.

 

[Lavey29]

Also keep in mind that you need to balance any increase in alk dosing with cal dosing too. They work together proportionally.

 

[k2-]

I will approach your problem differently - what are you trying to achieve ?

is it the number you are chasing ? Then no need to bother - natural sea water is at 7.6 ph

if I have one advice which I learnt or learning hard way is to go for stability - but if you still want get a calcium reactor and let it run once you stabilize.

all my failure just have one message for me - hands off and don’t solve what’s not a problem.

 

[AKL1950]

Also keep in mind that you need to balance any increase in alk dosing with cal dosing too. They work together proportionally.

I think I understand the ratios, but my calcium is still holding above 500. That may be because of the daily water changes. Do I need to dose calcium yet or wait till I see it moving down toward, say, the 450 area? Seems that if it’s stable at a high level, I wouldn’t want to be adding more.

 

[AKL1950]

I will approach your problem differently - what are you trying to achieve ?

is it the number you are chasing ? Then no need to bother - natural sea water is at 7.6 ph

if I have one advice which I learnt or learning hard way is to go for stability - but if you still want get a calcium reactor and let it run once you stabilize.

all my failure just have one message for me - hands off and don’t solve what’s not a problem.

Lol! Yeah, that’s something I keep having to relearn. Not chasing numbers here, but more trying to learn what makes the numbers what they are. I think my system is quite stable, for as young as it is and I’m not trying to hit a specific number come hell or high water. I think it’s more that I’m trying to learn and understand how and why all the chemistry works and how it changes with actions I do or the growth in the tank does. I see how is slowly creeps down and I want to see if I can “slowly” creep it back up. That will give me a better understanding of how all the chemistry works. I do understand that stability is King, but if I can tweak it up very slowly, I assume I will be rewarded with better coral growth. Then, try to keep my stability at that point.

 

[k2-]

Agree - I have burnt quite a lot with chasing numbers - also what I have learnt slow means over months not a week one of the very well respected reefer here said “nothing goes wrong in a reef suddenly and nothing fixes” - I have a bad habit of experimenting with my setup and I pay for it more than real rewards but atleast makes me close to an authority on what not to do rofl

 

[Randy Holmes-Farley Verified Community Expert]

is it the number you are chasing ? Then no need to bother - natural sea water is at 7.6 ph

It varies a bit day to night, especially in lagoons, but pH is rarely 7.6 in the ocean. PH 8.1-8.2 is a typical average.

 

[k2-]

It varies a bit day to night, especially in lagoons, but pH is rarely 7.6 in the ocean. PH 8.1-8.2 is a typical average.

@Randy Holmes-Farley I agree and i should go onto correct my post - it was the alk i was referring to. Just wanted to acknowledge.

 

[Lavey29]

I think I understand the ratios, but my calcium is still holding above 500. That may be because of the daily water changes. Do I need to dose calcium yet or wait till I see it moving down toward, say, the 450 area? Seems that if it’s stable at a high level, I wouldn’t want to be adding more.

If your dosing 2 part then whatever you dose for alk should be the same for Calcium. However, when my tank was new and corals were being added, I started dosing around the 7 month mark. I noticed that it seemed I needed more alk then calcium initially to keep numbers in range. At 10 months when coraline started thriving then my cal dose balanced out even with my alk dose and I have kept them equal since then.

You should only be dosing if your weekly water changes do not keep up with current demand for alk and calcium. Magnesium does down very slowly and generally a once a week hand dose suffices if needed. It goes down 1/10th the rate of alk and calcium.

 

[AKL1950]

If your dosing 2 part then whatever you dose for alk should be the same for Calcium. However, when my tank was new and corals were being added, I started dosing around the 7 month mark. I noticed that it seemed I needed more alk then calcium initially to keep numbers in range. At 10 months when coraline started thriving then my cal dose balanced out even with my alk dose and I have kept them equal since then.

You should only be dosing if your weekly water changes do not keep up with current demand for alk and calcium. Magnesium does down very slowly and generally a once a week hand dose suffices if needed. It goes down 1/10th the rate of alk and calcium.

Yes, that’s what I’m seeing. Alk has started dropping and Calcium has very slightly started dropping. I suspect as you, in about a month I’ll have to start dosing the calcium As well. Coraline is really starting to take off, so it shouldn’t be long before I see the calcium start down.

 

[Randy Holmes-Farley Verified Community Expert]

Yes, that’s what I’m seeing. Alk has started dropping and Calcium has very slightly started dropping. I suspect as you, in about a month I’ll have to start dosing the calcium As well. Coraline is really starting to take off, so it shouldn’t be long before I see the calcium start down.

IMO, that lag may just be a mathematical effect combined with mediocre tests.

A drop of 1 dKH (a 14% drop from 7 dKH) is easy to detect and is considered significant, but no hobby test will reliably detect the corresponding 7 ppm calcium decline (a minuscule 1.7% drop from 420 ppm).

Rising nitrate also depletes alk.