Persistently High Alkalinity Level??

[Nanook01]

Persistently High Alkalinity!!
Hi, I have been experiencing a high alk reading for sometime now. My alk has been 5.2meq/L or 14.5dKH for the last several weeks. My calcium has held at 440-450 for several weeks as well, although I do see a downward trend with the calcium level. Tonight my calcium level is 435. I have had a calcium reactor up and going since June 6th. Effluent pH of ca++ reactor is about 6.6 and alk of effluent is only = 26-27dKH.

I am worried that this persistently high alk will eventually drive my calcium level down. Is there something I should do to decrease the alkalinity to a more natural level of 3.5-4ish??

Thanks for any suggestions!!

Nanook

 

[Mouse]

I didn't think that Alkalinity would present such a problem. It is true that the calcium will precipitate itself if in a high concentration of Alkalinity, but what that level is i dont know, love to find out though?

[ August 08, 2001: Message edited by: Mouse ]

 

[jdeets]

Nanook--here's what I would do. Raise the pH of your effluent to 6.8-6.9. Maintain the current effluent flow rate. See if your alk and Ca trend down. Keep cutting back on the Ca rxr output until you see a downtrend. Chemically speaking, for each 1 meq/L your alk drops, Ca should drop 20 ppm. So if your alk goes to 3.2, your Ca should still be at 400 ppm based on the original figures you provided. Once you get your alk where you want it adjust your Ca rxr to maintain that level, and if you want Ca a little higher, bump it up with Calcium Chloride. Once you get it balanced and the rxr dialed in, you should be able to test for alk only and know your Ca level without testing it.

Always adjust your Ca rxr based on alk as that is the more unstable biomineral component (as compared to Ca). Ca will remain relatively stable with variations in alk when using a balanced method of supplementation such as a Ca rxr. (i.e., you could lower your alk to zero and you'd still have Ca of 350 ppm.)

HTH

 

[Nanook01]

Thanks James, I will give this a try. I appreciate your advice. I will just decrease the BPM slightly to get a pH of 6.8-6.9 on the effluent. Then test to see if a downward trend develops and wait for alk to come down.

Dave

 

[Nanook01]

Someone offered this information to me on RC. I figured I would throw it out here for whoever wants to comment or try it out. www.athiel.com/lib2/tips/lowering.html

nanook