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  #1  
Old 01/05/2008, 05:01 PM
mmotown mmotown is offline
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I can't get my effluent ph down!!!

I have a MRC dual chamber. Just changed my media in my first chamber to Schuran media and I have ARM in my 2nd. My effluent drip won't fall below 7.0. It has almost been 4 days. What's the problem? I don't want to put too much CO2 in the tank. With ARM it wouldn't take anytimne for the ph to fall. with ARM my C02 bubble count was 1ble per sec. With Schuran I have to run almost a steady fast stream and the cO2 runs all day. Is this normal or should I go back to ARM?
  #2  
Old 01/05/2008, 08:45 PM
skairik skairik is offline
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I recall reading in a thread a while back about Schuran media needing more CO2 than other media types. I also have a MRC dual chamber reactor (CR4 model) and I have ARM in it but my problem is it keeps getting "vapor locked."
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  #3  
Old 01/06/2008, 12:34 AM
marsh marsh is offline
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I believe according to directions of the MRC dual chamber Ca reactor that 2nd stage effluent will be .3-.5 pH units greater than the 1st chamber. So it sounds like you are OK.

One suggestion...get a pH controller...put the probe in the 1st chamber and regulate to your desired pH ~6.5-6.6. Then follow the online Ca setup calculator in the chemistry forum.
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Old 01/06/2008, 10:45 AM
mmotown mmotown is offline
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Quote:
Originally posted by skairik
I recall reading in a thread a while back about Schuran media needing more CO2 than other media types. I also have a MRC dual chamber reactor (CR4 model) and I have ARM in it but my problem is it keeps getting "vapor locked."
What do you mean by Vapor Locked?
  #5  
Old 01/06/2008, 10:47 AM
mmotown mmotown is offline
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Quote:
Originally posted by marsh
I believe according to directions of the MRC dual chamber Ca reactor that 2nd stage effluent will be .3-.5 pH units greater than the 1st chamber. So it sounds like you are OK.

One suggestion...get a pH controller...put the probe in the 1st chamber and regulate to your desired pH ~6.5-6.6. Then follow the online Ca setup calculator in the chemistry forum.
My tank PH is 8.1-8.3. My effluent seems to rise during the day. It's at 7.3. I don't want to overload my system with C02. What will excess C02 do?
  #6  
Old 01/06/2008, 02:29 PM
Randy Holmes-Farley Randy Holmes-Farley is offline
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The primary effect of CO2 is to reduce pH. If the pH is not too low, there is no excess CO2.
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  #7  
Old 01/06/2008, 03:28 PM
mmotown mmotown is offline
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So Randy I am safe to up my C02?
  #8  
Old 01/06/2008, 05:16 PM
skairik skairik is offline
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Quote:
Originally posted by mmotown
What do you mean by Vapor Locked?
Basically my effluent drip keeps "drying" up on me. I think I might have it figured out now though.
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  #9  
Old 01/06/2008, 07:02 PM
marsh marsh is offline
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Quote:
Originally posted by mmotown
My tank PH is 8.1-8.3. My effluent seems to rise during the day. It's at 7.3. I don't want to overload my system with C02. What will excess C02 do?
Right now it appears you are OK. The risk I see you having is inappropriatly lowering pH by increasing your CO2 bubble rate. pH in the 1st chamber should not fall below 6.4-6.5 in order to avoid turning the reactor substrate to mush. This is why I advise using a pH probe/controller in the 1st chamber. Set the pH and forget about it other than occasional pH probe calibrations. Measure the efffluent alkalinity and tank alkalinity and follow the online calculator Calcium Reactor Setup
  #10  
Old 01/07/2008, 07:23 AM
Randy Holmes-Farley Randy Holmes-Farley is offline
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I would try to gauge the amount of CO2 added by whether it is meeting the demand for alkalinity in the tank, not by any measure of the pH in the reactor or the effluent.
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  #11  
Old 01/07/2008, 11:10 AM
marsh marsh is offline
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Randy,

I agree the to regulate Ca reactor variables so as to match system alkalinity consumption with Ca reactor alkalinity output given calcium levels do not rise. My arguement has to do with simplifying Ca reactor setup.

The way I handle alkalinity is to measure the alkalinity of the final effluent and adjust the drip rate of the effluent to match tank consumption. I keep my pH in the reactor chamber near a set point to dissolve media but not disintegrate it and thus maintaining a constant effluent alkalinity. In this way only one variable is changed, effluent drip rate, to match alkalinity consumption. My assumption is that with a pH contoller, with the probe in the reaction chamber, the alkalinity of the effluent will be constant over a wide range of drip rates. This gives a relatively wide dyanamic range in which to match alkalinity consumption with reactor alkalinity consumption by changing one variable, effluent drip rate. It also considerable simplifies reactor "tuning".

Your method, I assume, alters the CO2 bubble rate so as to dissolve media and not disintegrate it but keeps the drip rate constant. Altering the chamber pH by adjusting the CO2 bubble rate alters the effluent alkalinity which with a constant drip rate matches tank alkalinity consumption. Again changing one variable, CO2 bubble rate? Or do you also change the effluent drip rate? If only the CO2 bubble rate is altered to match alkalinity output with consumption, I believe, you are limited by the accuracy of bubble counting, bubble rate incremental change, effluent pH measurement and perhaps by dynamic range of your alkalinity adjustment. The dyanamic range of alkalinity output at a constant drip rate is limited by a pH range of 6.5 to ?7.6. Is this a real issue? Also is the change in alkalinity linear with reactor pH change? If you also alter drip rate I presume you will also alter the effluent alkalinity at a set bubble rate as the dwell time changes. Is this actually an issue with reasonable incremental changes in drip rate? Anyway, once set with alk output equal to consumption, everything is copacetic. However, the matching process takes a good while just changing one variable.

I do not have a dual chambered reactor, but the intial question had to do with lowering the final effluent pH of a dual chambered reactor. The final effluent pH is ~7.0 making the 1st chamber ~6.5-6.7. Increasing his CO2 bubble rate to increase effluent alkalinity to match tank consumption would put the media in the first chamber at risk. For example, an effluent pH of 6.5 would mean the 1st chamber pH is 6.0- 6.2 or so putting the media at risk. Decreasing the CO2 bubble rate and thereby increasing the 1st chamber pH/decreasing effluent alkalinity may also place the pH in chamber too high for the 2nd chamber media to be of use in terms of alkalinity contribution. I always thought the 2nd chamber was mainly to increase effluent pH and not alkalinity anyway.

IMHO a ph controller with the probe in the first reactor chamber will simplfy setup and will put his 1st chamber media at less risk. In another thread his effluent pH was 6.5.

Last edited by marsh; 01/07/2008 at 11:16 AM.
  #12  
Old 01/07/2008, 12:15 PM
marsh marsh is offline
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BTW my suggestion is moot because MRC dual Ca reactors do not have a pH probe port for either chamber. But should mmotown wish to a probe port could be purchased and a hole drilled in the top to seat it.
  #13  
Old 01/08/2008, 02:06 AM
madadi madadi is offline
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i agree with marsh, i had a hole drilled in the first chamber and i installed a probe. it was easy. makes me life a lot easier. i keep the pH constant in the first chamber at 6.7 i dont care what it is in the second chamber because i know it will always be a few .2-.5pH higher. all i adjust is the drip rate. its hard to keep it constant but its as easy as it can get.

i would also switch to the ARM course media in both ractors. thats what i use and i have no problems. it dissolves at a pH of 6.8 at a real nice rate.
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  #14  
Old 01/08/2008, 06:01 AM
Randy Holmes-Farley Randy Holmes-Farley is offline
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That's certainly a fine way to do it. I just don't think folks need to obsess with the pH value if they are getting adequate alkalinity in the tank. The original poster may have a fine situation, aside from worrying about the pH.
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  #15  
Old 01/10/2008, 08:59 PM
mmotown mmotown is offline
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Randy and Marsh I am sending you guys a pm.
  #16  
Old 01/10/2008, 09:02 PM
mmotown mmotown is offline
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Not fair Randy!!! Where's your Pm button?
  #17  
Old 01/11/2008, 07:43 AM
Randy Holmes-Farley Randy Holmes-Farley is offline
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Too many pm's
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  #18  
Old 01/11/2008, 09:08 AM
mmotown mmotown is offline
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Randy today I am receiving my new rx. I don't understand that Ca calculator. I have always measured the ph from my effluent and monitored ALK and ca in my tank. I never measured the put out of the effluent and perhaps that's why my ALk would fluctuate from time to time. What I mean is some people know their tank consumption and the now what each drip is contributing to their ALK/CA needs. I was on the c02 bubble count and effluent drip level. If my parameters were fine then I assumed my settings etc were fine. I know I a missing something. Now I want to do it right so my tank can be stable. How do I proceed? Teach me Sensei!!!!!
  #19  
Old 01/11/2008, 09:13 AM
Randy Holmes-Farley Randy Holmes-Farley is offline
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FWIW, I'm not especially fluent with the reactor calculator as I do not have one so have not used it much.

In general, if the tank alkalinity is fine, and the tank pH is not too low, there is no need to adjust anything.

There are a bunch of heavy reactor users (including the calculator author) in the Reef Chemistry forum that could certainly walk you through how they use the calculator if you post a question there.
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  #20  
Old 01/11/2008, 09:40 AM
bluewatercandy bluewatercandy is offline
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Where do you purchase a Ph probe port? I have an older Geo reactor and it does not have one. I measure the Ph in a cup fed by the reactor drip. This cups Ph tends to be .2 to .5 higher than the actual Ph in the reactor. I think an in reactor Ph reading would be much more accurate for my setup...
  #21  
Old 01/11/2008, 11:10 AM
mmotown mmotown is offline
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Quote:
Originally posted by bluewatercandy
Where do you purchase a Ph probe port? I have an older Geo reactor and it does not have one. I measure the Ph in a cup fed by the reactor drip. This cups Ph tends to be .2 to .5 higher than the actual Ph in the reactor. I think an in reactor Ph reading would be much more accurate for my setup...
You would have to contact GEO or the company you bought it from. Possibly a google key word search. I know for the Koralin 1502 they make a ph probe port top.
 

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