Kalk Treatment and weird ph effects??

[Jan]

Hi

I'm puzzled. I just bombed a bunch of majanos in my 140g system with kalk paste. I think I used about 3ml of kalk paste overall; maybe 3.5ml.

Before I started the treatment, my ph read 8.20. I left the kalk in the tank for 30 minutes, then checked my ph and it had jumped to 8.53. At this point I turned off the CO2 in my reactor and started syphoning out the residual sediment.

I finished that about 15 minutes later, checked my ph again and it had dropped from 8.53 to 7.75! What the heck??!

It's been about 45 minutes since that time and now the ph has gradually risen to 8.04.

Can anyone explain the chemical reaction/s that affected the ph this way?

And what is the safe limit of kalk paste to put in at any one time? I've used similar amounts in the past and not had this result.

 

[Velamondry]

Here is a pretty good Faq list ive found about kalk and reactors, good site overall if your not familiar with it. Might help if your willing to dig through it some. http://www.wetwebmedia.com/kalkh20faq2.htm

hope it helps.

 

[Boomer]

What is the Alk and Ca++ as these are related ? Your paste may have been degragated or gotten degragated upon addition and sitting, thus pulling out not only Ca++ but CO3, thus killing you Alk and a drop in pH.

First, to really learn about kalk read these.

What Your Grandmother Never Told You About Lime
http://reefkeeping.com/issues/2005-01/rhf/index.htm

The Self Purification of Limewater (Kalkwasser)
http://www.advancedaquarist.com/issues/may2003/chem.htm

The Degradation of Limewater (Kalkwasser) in Air
http://reefkeeping.com/issues/2003-05/rhf/feature/index.htm

Magnesium and Strontium in Limewater
http://www.advancedaquarist.com/issues/dec2003/chem.htm

 

[Jan]

Thankyou Boomer....

Your paste may have been degragated

I'm not sure what you mean by this--degraded? What would be the impact, if that was the case, and what could cause that to happen? It only sat for a few minutes before I added it.

My alk has been hovering around 6.5 dhk lately although I have been trying to bring it up. Last night it tested 6.3 dhk, a few hours after the kalk dosing. I added a half tablespoon of Reef Builder at that time. (I am a zeovit user so I try to keep my alk at 7-8 dhk).

I wonder if I shouldn't have turned off the CO2 on my Rx when I saw the ph rise to 8.53 (?). I assumed that the alk would follow...

I don't know what my Ca level is but I'll test it when I get home this evening.

OK, editing to add that I read most of these links and I understand what the degradation of the kalk means now, but I still don't get how that relates to the situation I experienced, as it seems to have more to do with sub-optimizing the usefulness of kalkwasser solution as a Ca supplement (?) as opposed to its effects on ph. Or did I miss something?

 

[Boomer]

If your paste was new then no I would thing it not. Degragated is from Kalk sitting to long. I though about turning off your reactor but that does not make sense either, as IMHO the pH should have not dropped so quickly reactor or no reactor. Actually the pH should have not dropped at all. Your Alk has not dropped enough to really do anything. What ever happen, if something did happen, there was a release or creating of CO2 from something which makes no sense. Kalk, as you know, raises the pH and Alk and removes CO2. I wonder if was just not some coincidently probe issue, which is the only thing that makes any sense. I'll ask Chris, another Randy kind of guy, he is into these types of reactions big time.

It just hit me You said you shut off the CO2 and the reactors was still running. At times, under the right conditions, if reactors are not run quite correctly they can developed CO2 pockets in them. If these pockets get purged out the pH can drop like a rock. So, I'm thinking, that with the CO2 on, you had a pocket and when it was shut off this changed the dynamics of the reactor and that CO2 pocket was purged out. I just remembered this form a article I got to review 2 years ago, that never got published on this issue. I'll bet this is what hapened. If the pockets are to big they can take out the whole tank. Is this a DIY reactor where this may be more common ?

 

[Jan]

It just hit me You said you shut off the CO2 and the reactors was still running. At times under the right conditions if reactors are not run quite correctly they can developed CO2 pockets in them. If these pockets get purged out the pH can drop like a rock. So, I'm thinking that with the CO2 on you had a pocket and when it was shut off this changed the dynamics of the reactor and that CO2 pocket was purged out.I just remembered this form a article I got to review 2 years ago that never got published on this issue. I'll bet this is what hapened. If the pcokets are to big they can take out the whole tank. Is this a DIY reactor where this may be more common ?

Holy Crap, Boomer, I bet that is what happened! :shock:

This is not a DIY reactor but I have had problems with it, on and off, from the beginning. Frequently it plugs up and the effluent stops dripping, and CO2 builds up inside. Basically I can not get the drip level low enough where I want it to be without causing an air pocket in the line and CO2 buildup in the reactor.

This is an Octopus dual-stage reactor, very big, with an Octopus pump attached. So far I have replaced the regulator/solonoid, pump, and feed pump on this reactor. Feed pump is an eheim 1250.

At one point DonW recommended replacing the feed pump with a dosing pump to pull water out of the reactor instead of pushing it through the reactor (but I didn't do it).

I really don't want to take the risk of this reactor "taking out" my tank. Do you recommend that I get a new reactor, or do you think that replacing the feed pump with a dosing pump would solve my problem?

Thanks very much for helping me with this; it's very much appreciated.

 

[Boomer]

You bet Jon

I would PM Don and see what he thinks as I think he is correct.