Please tell me about alkalinity

[Mike&Pam]

I have recently had problems with low alkalinity. I have posted this question several times but have not really been answered. I have two alk test kits and both say the alk should be at different levels. I know natural seawater is 2.5 meq. One kit says (the seachem kit) says that the aquarium should be kept at 4-6 meq. The other (the red sea, which i believe is more accurate) says that it should be kept at the same as natural seawater. All my other parameters are fine. All I'm asking is what level should the alk be, regardless of my coral load?

 

[Dargason]

I hear your frustration. I didn't get the answers I wanted to my recent questions on controlling alkalinity. So I did a little bit of research myself.

Here's a link that you might find useful:
http://saltaquarium.about.com/gi/dynamic/ offsite.htm?site=http%3A%2F%2Fwww.actwin.com%2Ffish%2Freefkeepers%2Freefkeeper1.html%231.3.1

Basically, an alkalinity of 3-4 is recommended, but you're probably OK between 2.5 to 5. Natural seawater is about 2.5.

Basically, alkalinity is a measure of the pH buffering capacity of your tank. Physically, it is a measure of the concentration of CaCO3 in the water. (Actually, this is carbonate hardness, but in seawater carbonate hardness is almost the same as alkalinity, so most people ignore the difference.) Higher alkalinity means that your tank will be less susceptable to swings in pH resulting from an acid, such as CO2.

In addition to buffering against swings in pH, correct alkalinity (correct carbonate hardness) helps your corals grow by provided CaCO3 that they need.

Here's another good link: http://web2.iadfw.net/westcott/Alkalinity.html

[ October 31, 2001: Message edited by: Dargason ]</p>

 

[randy holmes-farley]

Seachem recommends a huge alkalinity that would be a big problem in natural seawater. The reason that they recommend it is because they add a huge, unnatural amount of borate to their salt mix that pushes alkalinity through the roof. So if you use their salt, which I don't recommend for this very reason, you need very high alkalinity.

If you use any other salt mix, an alkalinity of 2.5 to 4 meq/L works fine for most people.