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i have a dual reactor hooked up to my tank. i have held a pretty steady ph of 8.2-8.3 for a year. over the last 2-3 months it has fallen to the 7.8 at night to 8.05(ph monitor) in the day. i have a reverse daylight refugium. calcium is at 460. alkylinity has faltered somewhat to about 9 dkh. i buffered ph to 8 last week but it has fallen again
should i keep buffering it up, or change my reactor effluent ? right now running 150 bubbles minute and fast flow 100 ml minute.
 

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If your dual reactor (I'm not familiar w/ it) incorporates CO2 injectors to assist calcium dissolution, you may be dumping too MUCH CO2, acidifying the water.

Excess carbonic acid would eat into your buffers and keep driving your pH south.




Again, I'm not familiar with your 'dual' device.


hth
horge
 

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Wasabi:

Consider getting a Pinpoint pH controller. They are expensive, but assuming you have an electical (normally closed) manifold on the CO2 bottle, you can avoid this problem. They are expensive, but worth it for avoiding this problem (and for a handy dandy pH monitor to boot). FWIW, I have a Myreef CA reactor and it works fine with the pH controller.

How exactly are you dosing the CO2 into the CA reactor - are you continuously adding CO2? If so, that is probably the problem.

K.M.
 

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I could be wrong here, but I think your effluent PH out of the second reactor chamber is actually a bit high. From what I've read, I think you need a PH of approx. 6.7 or a bit lower to disolve the media.
 

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wasabi said:
i have a dual reactor hooked up to my tank. i have held a pretty steady ph of 8.2-8.3 for a year. over the last 2-3 months it has fallen to the 7.8 at night to 8.05(ph monitor) in the day...
Before you do anything that involves spending a lot of money or making a set of huge changes, take the time to replace your battery in the meter and/or clean your pH probe. If the probe is more than 18 months old, think in terms of replacing and calibrating it with fresh standards.

The safest way to clean mineral deposits from your probe is to soak it in white vinegar for an hour or two, then rinse it in RO water and soak it for 10 more minutes in clean RO water and calibrate. It will help to remove the biofilm from it as well. To do this, put 1 tablespoonful of Chlorox (Sodium hypochlorite solution-household bleach) in a clean class container and dilute it with 9 more tablespoonsful of RO water. Soak for 10 minutes, the rinse in clean RO water and soak for 10 more minutes. Recalibrate.

To recalibrate the Pinpoint meter and probe, use the little packets of standards, they are much more reliable when opened fresh and in date than the bottles of standards (which start to wander from the exact pH of the standard as soon as they are opened). Before opening the packets of standardizing solution, bring them to tank temp (throw the unopened packets in the sump for a bit, about 10 minutes). Get a ceramic mug for each standard to test, and put it in the sump as well. When ready to test, both the mug and the standards will be at tank temp. Open the 7.0 pH packet at the top only, put it (upright) in a water bath in the mug (this prevents temperature change induced variations), then put the probe into the standard solution and stir it gently. Set a timer for 10 minutes, then check the reading at the end of that period and adjust the reading to the standard's pH (7.00). Rinse the probe with fresh RO water, then shake any excess water off the probe and place it in the 10 or the 4 pH standard, and set the timer for 10 minutes. At the end of that time, adjust the reading on the meter to the pH of that solution, rinse in RO water, shake off any excess water, and retest the 7.0 standard again for 2 or 3 minutes. It should read to within 0.01 pH units of 7.00. If not, repeat the calibration process. If it passes the retest, rinse the probe and put it into service.

If this doesn't fix the problem, repost and I will make other suggestions. H ope this helps.
 

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Discussion Starter · #7 ·
thanks TD, i have been calibrating with the bottled versions. i'll order some of the packets and try to recalibrate.
 

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wasabi said:
thanks TD, i have been calibrating with the bottled versions. i'll order some of the packets and try to recalibrate.
The most important part will be the cleaning and removal of the biofilm, but because these processes will change your calibration, it will be required as well. You should definitely go with the little sachettes of standards as opposed tio the bottles though.

btw, Cali, the purpose of using the second chamber of reactor media is NOT to increase the Ca saturation, as it will be plenty saturated when it goes through the first chamber, rather, it is to raise the pH of the effluent by reacting the free CO2 with some aragonite media to reduce the amount of carbonic acid being returned to the tank. A pH of 6.7 is appropriate for a single column reactor though. Passing the effluent from the first column through the second chamber does pick up a little more Ca and alk, but the primary reaon for using the 2nd reactor column is to remove excess CO2 from the effluent. You can increase the amount of Ca and alk going into the tank with one, but it will require cranking up your CO2 a bit, and doind that really defeats the purpose of using the second reactor chamber.

hth
 
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