High Alkalinity what does it really cause

[maroun.c]

Hi,
What does really ahppen when you run High Alk in a tank. Understand that low alk can cause coral skeletons to melt and that affects the flesh on top but what happens if your alk is too high?
Would assume you'd have coral growth that tissue might not be able to keep up with but how does that kill or affect corals?
One other question is what really kills corals in an alk swing.
Thanks.

 

[Randy Holmes-Farley]

There are a variety of things that high alkalinity does.

First, it increases the likelihood of precipitation of calcium carbonate on things like pumps, heaters, and sand.

Second, it spurs some hard corals and coralline algae to grow faster since getting enough carbonate can be a rate limiting step in calcification (skeletal growth).

Finally, some SPS corals in a very low nutrient environment with high alkalinity may suffer "burnt tips", which might be due to the tissue being unable to keep up with the skeletal growth, leaving very thin tissue which might be more susceptible to burning by high light/UV levels.

Corals that have issues with alk swings may be suffering from a temporary mismatch between their ability to take up bicarbonate and the internal demand for it.

 

[maroun.c]

Thank for the info Randy

 

[Randy Holmes-Farley]

You're welcome.

Happy Reefing.

 

[Homebrwr]

So what are you considering to be high ?

 

[greg 45]

Please help me understand.
You can run high allk with higher nutrient give a number for example
Low nutrient 7 to 8 need low alk why
Where is the sweet spot

 

[RafaelsReef]

Will gfo cause alk swings enough to keep SPS from thriving?
Sorry if its off topic.

 

[Randy Holmes-Farley]

So what are you considering to be high ?

I'd try to limit the high end to 11 dKH for precipitation isues and maybe 9 dKH if you keep a ULNS SPS tank and want to avoid burnt tips.

 

[Randy Holmes-Farley]

Will gfo cause alk swings enough to keep SPS from thriving?
Sorry if its off topic.

Not usually.. It may encourage skeletal growth of corals by reducing phosphate and may increase precipitation of calcium carbonate on and near the GFO, but the changes in alk (and calcium) are usually low enough to not be a concern.

 

[Randy Holmes-Farley]

Please help me understand.
You can run high allk with higher nutrient give a number for example
Low nutrient 7 to 8 need low alk why
Where is the sweet spot

Not sure what you mean by a sweat spot. If not a ULNS tank, it seems not not matter what the alk is (say, 7-11 dKH), but corals can grow faster at higher alk, if that is a goal.

 

[trio91]

Not sure what you mean by a sweat spot. If not a ULNS tank, it seems not not matter what the alk is (say, 7-11 dKH), but corals can grow faster at higher alk, if that is a goal.

a question for you good sir....after testing my tank here is what i got (Mag-1400, Cal-600, Alk- 6, Ph-8.1)....my alk is my issue... after searching for info on this it seems to me that it is low. without having the rest of the parameters in-front of me (to give to you as i remembered these in particular from last night) would you be able to guess what issue could be? i am using kalk in my top off which is why i am assuming the mag and cal is high....but does kalk affect Alkalinity? should i be dosing Alk separately? does temperature effect Alk? i know my tank has been running hotter than normal with the heat wave we've been having here.

i am sorry to bombard you with a ton of questions but it seems like my monti's growth has been stunted and i am not sure of what the cause is

 

[Randy Holmes-Farley]

Many corals may suffer at 6 dKH. I'd raise it.

Very long term use of limewater will slowly raise calcium relative to alkalinity. So using a lower calcium salt is preferred.

I'd switch to baking soda or washing soda for a while instead of the limewater (or in addition to it) to get the alk higher and let the calcium decline a bit.

I have the same issue and discuss it here:

https://www.reef2reef.com/blog/my-triton-testing-results-by-randy-holmes-farley/

from it:

Calcium (Ca). In my reef aquarium, I use only Instant Ocean salt and I have not added any additional calcium except as limewater for a number of years (during which time I have continued regular 1% daily water changes). So why is my calcium level (472 mg/L) higher than one would normally expect for Instant Ocean (maybe between 350 and 400 mg/L)? That long term rise in calcium is actually the expected result when using limewater to maintain alkalinity.

Limewater adds calcium and alkalinity in exactly the same proportions as in pure calcium carbonate. So if that is what is used by corals to make skeletons, and what precipitates on pumps and such, then calcium would stay constant.

But both magnesium and strontium get into growing calcium carbonate crystals in place of some of the calcium. A few percent of the calcium is replaced this way. Consequently, since the same amount of alkalinity (the carbonate) is used over time, and somewhat less than the balancing amount of calcium, calcium rises if alkalinity is maintained. I’m happy to see the result match the theory, and the calcium level seems fine to me.

 

[trio91]

Many corals may suffer at 6 dKH. I'd raise it.

Very long term use of limewater will slowly raise calcium relative to alkalinity. So using a lower calcium salt is preferred.

I'd switch to baking soda or washing soda for a while instead of the limewater (or in addition to it) to get the alk higher and let the calcium decline a bit.

I have the same issue and discuss it here:

https://www.reef2reef.com/blog/my-triton-testing-results-by-randy-holmes-farley/

from it:

Calcium (Ca). In my reef aquarium, I use only Instant Ocean salt and I have not added any additional calcium except as limewater for a number of years (during which time I have continued regular 1% daily water changes). So why is my calcium level (472 mg/L) higher than one would normally expect for Instant Ocean (maybe between 350 and 400 mg/L)? That long term rise in calcium is actually the expected result when using limewater to maintain alkalinity.

Limewater adds calcium and alkalinity in exactly the same proportions as in pure calcium carbonate. So if that is what is used by corals to make skeletons, and what precipitates on pumps and such, then calcium would stay constant.

But both magnesium and strontium get into growing calcium carbonate crystals in place of some of the calcium. A few percent of the calcium is replaced this way. Consequently, since the same amount of alkalinity (the carbonate) is used over time, and somewhat less than the balancing amount of calcium, calcium rises if alkalinity is maintained. I’m happy to see the result match the theory, and the calcium level seems fine to me.

so i can add pure baking soda like arm n hammer to raise my alk? and assuming i should be looking for a reading around 8 correct?

 

[Randy Holmes-Farley]

so i can add pure baking soda like arm n hammer to raise my alk? and assuming i should be looking for a reading around 8 correct?

8 dKH is a fine reading, and yes, Arm and Hammer baking soda is a good method. Dissolve in some fresh water first. Bake it (400 deg F, 1 h) or buy sodium carbonate if you also want a pH boost from it.

This calculator shows how much to use:

http://reef.diesyst.com/chemcalc/chem_calc3.html

 

[trio91]

8 dKH is a fine reading, and yes, Arm and Hammer baking soda is a good method. Dissolve in some fresh water first. Bake it (400 deg F, 1 h) or buy sodium carbonate if you also want a pH boost from it.

This calculator shows how much to use:

http://reef.diesyst.com/chemcalc/chem_calc3.html

that calculator is awesome....thank you very much for the link....side note the calculator did not mention any cooking/baking...is there a reason for that?

 

[Homebrwr]

I'd try to limit the high end to 11 dKH for precipitation isues and maybe 9 dKH if you keep a ULNS SPS tank and want to avoid burnt tips.

Thank you. I try to maintain 9...

 

[joekool]

that calculator is awesome....thank you very much for the link....side note the calculator did not mention any cooking/baking...is there a reason for that?

Baking it makes it carbonate instead of bicarbonate right out of the bag. Bicarbonate will raise the alk level without effecting ph as much as carbonate will. He is saying if you bake it then mix with ro di it will boost ph.

 

[trio91]

Baking it makes it carbonate instead of bicarbonate right out of the bag. Bicarbonate will raise the alk level without effecting ph as much as carbonate will. He is saying if you bake it then mix with ro di it will boost ph.

Aaahhh ok....thank guys....i will attempt this tonight and keep everybody posted

 

[Randy Holmes-Farley]

I discuss the baking as part of a DIY two part here:

An Improved Do-it-Yourself Two-Part Calcium and Alkalinity Supplement System by Randy Holmes-Farley - Reefkeeping.com

 

[trio91]

I discuss the baking as part of a DIY two part here:

An Improved Do-it-Yourself Two-Part Calcium and Alkalinity Supplement System by Randy Holmes-Farley - Reefkeeping.com

thank you for that...(i just read the article section on ALK)......last question (i promise) how long will the solution last? given that i would like to start dosing slowly will it loose its potency over time?