What do I need to know.. Alkalinity?

mony97

mony97

Member
So I have read a few things about alkalinity in our tank environments and have a descent understanding of it, however, a lot of the information I read became to technical (not that I am dumb, but a little to much right off the bat).
So I was wondering what are some of the basics, how can it help my tank, what does it interact with, etc. Any info or input on this is welcome :)
Thanks
 
ajroc31

ajroc31

Member
Simple, stupid, my understanding, it can be measured in dkh, which is calcium carbonate. Good, corals use it to build their skeletons. Calcium hydroxide, is the calcium that you see in liguid reactors. Both interact with each other. What you want, is a balance between the two, which could be reached at about 6-12 dkh and 420. When you have too much of either, it will not allow for the other to be a proper level. Alkalinity also interacts with ph. Lower the alk, less carbon molcules it takes to affect and drop ph. When you have high alkalinty, your ph will be more stable, cause it will require more CO2 to affect the ph drop, which is connected to Co2 levels in the tank. Acidic water has higher levels of it. So, it my understanding of alk. I am sure someone will give you a better explenation.
 
R

rcreations

Guest
Something to add, puple/pink coraline grows better when dkh is 8 or 9. So if you want lots of purple on your rocks, keep the dkh around 9. Of course, other factors are involved in having nice coraline... calcium, water flow, lighting.
 
bang guy

bang guy

Moderator
Alkalinity is technically the amount of resistance the water has to a change in PH. That is only part of the picture for reef tanks. It is also an approximation of the amount of carbonate (or bicarbonate) dissolved in the water.
Organisms that build structures of Calcium carbonate will require equal parts of Calcium and Carbonate. This includes all stoney corals, most soft corals, snails, clams, coralline, etc. Carbonate levels are normally much less than Calcium on a percentage basis, but are consumed at nearly identical rates. As a result Carbonate levels will decrease to critical levels much sooner than Calcium levels and yet most new hobbiests are typically obsessed only with Calcium levels.
An example of what I mean by dropping to critical levels:
The average salt mix will provide 400ppm Calcium and 2.5Meq/L Alkalinity. I'll use 125ppm ALK to better illustrate the usage. The majority of Alkalinity is provided by Carbonate unless you're using Seachem salt.
Let's assume a moderate coral load that consumes 40ppm of Calcium a week. This is a typical hobbiest tank. Obviously more coral will mean a faster consumption rate all other things being equal.
Week 1- Calcium = 400ppm Alk = 125ppm
Week2- Calcium = 360ppm Alk = 85ppm
Week3- Calcium = 320ppm Alk = 45ppm - this is less than 1Meq/L
Calcium consumption would actually stop sometime after week 2 because there's not enough carbonate in the water for organisms to build Calcium carbonate. Calcium is low but not critically low. Alkalinity is so low at this point that Calcium carbonate could actually begin dissolving.
 
dmanatee

dmanatee

Member
The simplest way to describe this refers to the capacity of the solution to buffer against drops in pH. A higher alkalinity will "typically" prevent quick changes in ph, and therefore should be monitored frequently. Also, Alkalinity isn’t one chemical but a mixture of many negatively charged ionic compounds including; carbonates, bicarbonates, borates, and hydroxides.
To make matters worse, alkalinity is often measures in two different scales.The meteric scale which uses the unit (meq/L) and the German scale of Karbonat (hardness) which uses the unit (dKH). To convert meq/L to dKH multiply by 2.8.
 
beaslbob

beaslbob

Well-Known Member
If you would look up dr randy holmes-farley's diy 2 part it should help explain. That method uses the alk measurement to determine when to dose calcium and alk.
my .02
 
mrdc

mrdc

Active Member
I just read a lot of that and will the rest from home. Is that the method you follow?
 
beaslbob

beaslbob

Well-Known Member
Originally Posted by mrdc
http:///forum/post/3266481
I just read a lot of that and will the rest from home. Is that the method you follow?
yes. along with dosing kalk in top off.
Very inexpensive. And very effective. Just measure alk and when alk drops down, dose. After a gallon of calcium and alk dosing then add magnesium.
 
bang guy

bang guy

Moderator
Originally Posted by mrdc
http:///forum/post/3266383
Why is this? (referring to the Seachem)
Unless they have changed their formula they have a lot of Borate in their mix for Alkalinity. This is OK for a while but the Borate is not used to build coral skeletons and it builds up over time. Your Alkalinity may be 3.5Meq/L but if only 0.5Meq/L of that is from Carbonate then your corals will not grow. A coral that cannot grow will die.
 
mrdc

mrdc

Active Member
So are you only referring to Seachem's salt? I use the Seachem alk and ca powders. Is the borate an issue with the alk powder?
 
bang guy

bang guy

Moderator
Originally Posted by mrdc
http:///forum/post/3266502
So are you only referring to Seachem's salt? I use the Seachem alk and ca powders. Is the borate an issue with the alk powder?
I don't know. Is there an analysis of the ingredients on the container?
Just to be clear, Borate is a fine Alkalinity additive. It's just not a substitute for Carbonate.
 
mrdc

mrdc

Active Member
Originally Posted by Bang Guy
http:///forum/post/3266588
I don't know. Is there an analysis of the ingredients on the container?
Just to be clear, Borate is a fine Alkalinity additive. It's just not a substitute for Carbonate.

The ingredients are:
Carbonate, bicarbonate, chloride, and sulfate salts of sodium, magnesium, calcium, strontium, and potassium. Doesn't say how much of each.
 
ajroc31

ajroc31

Member
Since we are on the topic of alk, has anyone used Seachem reef builder? I just got some today, and not sure if there is anything I should know about it.
 
mony97

mony97

Member
wow thank you to everyone who has contributed, this is greatly helping me with my understanding of how alk relates to my tank and why I should be monitoring it.
Question though, Bang you mentioned that once alk drops below we'll say 60ppm corals will stop growing because there is no longer sufficient levels of carbonate for them to make calcium carbonate, will this also effect coralline growth? and also I am assuming outside of dosing the best way to keep this in check is frequent water changes?
Thank you all again!! and keep any more info comin ;)
 
bang guy

bang guy

Moderator
Originally Posted by mony97
http:///forum/post/3266711
wow thank you to everyone who has contributed, this is greatly helping me with my understanding of how alk relates to my tank and why I should be monitoring it.
Question though, Bang you mentioned that once alk drops below we'll say 60ppm corals will stop growing because there is no longer sufficient levels of carbonate for them to make calcium carbonate, will this also effect coralline growth? and also I am assuming outside of dosing the best way to keep this in check is frequent water changes?
Thank you all again!! and keep any more info comin ;)
Yes, at low alkalinity levels coralline will also stop growing. Water changes can keep up with many tanks but it is related to the consumption rate and that's why it really needs to be tested. Dosing of some type is needed when there are a lot of corals unless you want to constantly change your water. The two-part additives, including the one Beaslbob pointed out, are great for smaller tanks. Calcium reactors are mostly hads free and automatic but the start up cost can be high.
 
bang guy

bang guy

Moderator
Originally Posted by mrdc
http:///forum/post/3266605
The ingredients are:
Carbonate, bicarbonate, chloride, and sulfate salts of sodium, magnesium, calcium, strontium, and potassium. Doesn't say how much of each.
That's an excellent ingredient list IMO.
 
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