Kalk and Alk

[phljess]

I have been using a kalk reactor for the past few months and it seems that my alk is always too low. I get it adjusted correctly using washing soda but then in a few days it is back down. My question is: why does my alk always seem to decrease while using a kalk reactor. I thought that kalk is supoose to be a balanced additive so why would my alk decrease and my cal stay the same?

 

[dreaminmel]

What test kit are you using for the alk?

 

[phljess]

"Aquarium Systems Fast Test"

 

[jdieck]

There is two posible explanations one of which is just perception.

a) A balanced additive is the one that provides Calcium and Alkalinity in the right ratio to create Caclium Carbonate in the coral calcification process. This does not mean that carbonate precipitation is the only process around. There are processes in the tank that consume alkalinity like nitrification which creates some acids that may consume alkalinity.
Check this article:
http://reefkeeping.com/issues/2004-12/rhf/index.htm

b) The second reason is perception. At balanced consumption a drop of 2.8 dKh in Alkalinity corresponds to a drop of only 20 ppm in Calcium so as an example, when your alkalinity drops from 9 to 6.2 which looks like a large drop, Calcium will drop say from 420 to 400 ppm giving the perception that alkalinity is consummed faster.

Now usually in a Kalk reactor the mix is rarely fully saturated, try using more powder, becasue the water added may contain a lot of CO2 and the CO2 degrades the mix turnign it into Calcium Carbonate there will be sediments that make belive there is still Kalk in there but might be mostly Carbonate so empty and refill the reactor more often and also increase the number of times it is stirred.
If the amount of evaporation is not large enough to add all the needed Kalk mix to maintain alkalinity then try increasing evaporation by using some fans over the water surface.

 

[jdieck]

By the way although AS Fast Test usually give you good aproximate results try doublechecking your test with a friends kit or at the LFS just in case.

 

[phljess]

Thanks a lot jdieck, I think I may need to increase the duration and amount of times my reactor stirs. Right now, I only allow the reactor to stir for 45 min twice a day. Do you think it would be better to let it stir for an hour, for times a day or let it stir for 30 min for times a day? Also I think I may be lossing some alk through the nitrogen cycle. How do most other reefers set their times for their reactors?

 

[phljess]

I have checked using two different Fast Test kits and they both gve me the same results.

 

[jdieck]

Stirring more often for short periods of times is better. Ideally you want periods of one or two minutes 20 times a day, unfortunatelly it is not easy to find a timer like that. So settle to as many times your timer can handle, five mintues each time shall be enough.
Also, I do not know the design of your reactor but idelly you want the fresh water entering all the way to the bottom so it gives the sediment a little stirr every time it goes in while exits trough the top. If the reactor does not have it you can install a tubing on the inside of the connector adapter that runs to the bottom of the reactor

 

[panic]

Wow, I only stir mine for 1 minute twice each day. The kalk stays suspended for hours. If not, it is time to change it out.

 

[phljess]

Where can I find one of these timers that can be programmed to go on and off twenty times a day?

 

[jdieck]

<a href=showthread.php?s=&postid=8041856#post8041856 target=_blank>Originally posted</a> by panic
Wow, I only stir mine for 1 minute twice each day. The kalk stays suspended for hours. If not, it is time to change it out.

As a side note, a well designed reactor does not allow the sediment to reach the top outlet no matter how long the stirring goes.

 

[jdieck]

<a href=showthread.php?s=&postid=8041889#post8041889 target=_blank>Originally posted</a> by phljess
Where can I find one of these timers that can be programmed to go on and off twenty times a day?

Close enough

http://www.electricsupplyonline.com/prod/intermatic-electronic_timers/dt17c_w005589.php

http://www.discount-hydro.com/timers.asp

http://www.elights.com/7dayprogheav.html