my pH increased with the addition of a calcium reactor

[BrokeColoReefer]

Yea, somehow thats the case. So here is the situation:

I run both a calcium reactor (korallin 3002) and a kalk reactor (ugly aquamedic).

My ph the last two months has been 8.0- 8.13.

I replaced the media a few months ago in my reactor and somehow forgot to plug in the recirculation pump. The feed pump still pushed water through the reactor and the co2 controller still controlled the pH at 6.4.

Two days ago, once i realized this, i plugged in the recirc pump and withing 4 hours my pH jumped from 8.1 to 8.43. I about had a heart attack with the sudden increase but it has held there now for three days. (8.4-8.45) I run a reverse daylight fuge so it stays consistent. Every thing seems fine, if not better then before, should i keep the kalk reactor on?

[jdieck]

What was your alkalinity level before and after? Chences are that once the recirculation pump was turned on, a rush of alkalinity was added thus not only counteracting the effect of CO2 but enough to have an increase in PH.

[BrokeColoReefer]

jdleck, some how i knew you would speak up, you where instrumental in helping me set up this reactor over two years ago.

Alk and calcium was 10/390 before, 11/390 now. The ph has not changed now for a few days. Before, the ph was always low when running the reactor, which is why i bought the kalk reactor. I wonder if i finally found the sweet spot on the reactor accidently...

[jdieck]

Think you did :D Now just insure the alkalinity level will be maintained and not to continue increasing.

[BrokeColoReefer]

I just went down to check the alk again, it has been a few days since i checked it. alk is 10.2, the reactor ph is running at 6.0 and the tank ph is 8.4 with the lights out and fuge lights on. Half the fun of this hobby is data. Cant wait to see what the next week brings.
Thanks jd.

[jdieck]

Insure that your reactor's probe as well as the one measuring the tank are well calibrated, 6.0 in the reactor seems low to be able to maintain 8.4 in the tank unless the effluent is minimal.

[BrokeColoReefer]

I will check, both probes where replaced about 2 months ago when i changed the media. The rate coming out of the reactor is in the neighborhood of 400 mL/min. The reactor will fluctuate between 5.9-6.4.

[jdieck]

<a href=showthread.php?s=&postid=13054163#post13054163 target=_blank>Originally posted</a> by BrokeColoReefer
I will check, both probes where replaced about 2 months ago when i changed the media. The rate coming out of the reactor is in the neighborhood of 400 mL/min. The reactor will fluctuate between 5.9-6.4.

40 or 400 ml/min? If 400, that is extremely high!

[jlinzmaier]

I was under the impression that it wasn't possible to lower the pH below 6.5 within a ca reactor. I think I read that on my Korralin instructions as I was setting it up. It indicated that if the pH was reading below 6.5 that the reading was incorrect becuase the co2 is unable to lower the pH below the 6.5 mark. Jdieck, is there any truth to that??

If so Brokecolereefer should really calibrate the probes and see what readings he gets then.

Jeremy

[jlinzmaier]

Doesn't mean it's a downright fact, but this is what was in my Korallin ca reactor manual.

First of all, it is impossible for the effluent pH to drop below 6.5. Below this value, no more CO2 can be dissolved into the saltwater. You may want to re-calibrate the pH Electrode if it
registers a value on the effluent of 6.5 or lower.

Any truth to that??

Jeremy

[jdieck]

<a href=showthread.php?s=&postid=13055406#post13055406 target=_blank>Originally posted</a> by jlinzmaier
Doesn't mean it's a downright fact, but this is what was in my Korallin ca reactor manual.

First of all, it is impossible for the effluent pH to drop below 6.5. Below this value, no more CO2 can be dissolved into the saltwater. You may want to re-calibrate the pH Electrode if it
registers a value on the effluent of 6.5 or lower.

Any truth to that??

Jeremy
Yes and No (I love to answer that instead of .. it all depends..):D

Actually it is possible to have a PH lower than 6.5 in the calcium reactor and readings around 6.3 are not unusual in normaly operating reactors.
What Korallin might be referring to is the effect of media disolution. While CO2 works to lower the PH, the dissolution of the media increases carbonate alkalinity which ends to increase PHso somewhere in the middle there is a point that dissolution complete counteracts the CO2 effect and a balance is achieved. At what level of PH can the balance be achieved? IMO there is not a set PH (Say 6.5) were we can say with certainty the balance is achieved because the rate at which CO2 dissolves in the water depends on variables like retention time, pressure, temperature, bubble size, pump impeller mixing effect etc. while the media dissolution depends on amount of media, retention time, flow trough the media, media particle size, water inlet initial alkalinity, effluent volume and so on. In summary each reactor or situation will have it's own balance PH level.
If you had a reactor with no or very little media chances are you could reach a PH level way lower than 6. In any case I could assume that Korallin might have run some tests and determined that the typical PH balance point for their reactors is somwhere "around" 6.5
In my particular reactor, if I increase the CO2 trying to farhter lower the PH, I reach that balance at around 6.4 where I start getting CO2 bubble formation on the top of the first chamber but again that is a level for my reactor and mine only given all the set conditions around its operation.

In any case I would consider anything below 6.3 unusual and may warrant at least a calibration check.

[jlinzmaier]

jdieck

Thanks for the incredibly detailed info!
Jeremy

[BrokeColoReefer]

OK i went down to check the rate, its in the neighborhood of 250 mL/min, not 400. The ph probe in the reactor is reading 5.98. I checked it against the ph probe for the tank, the tank pH probe reads 6.12, so at the very least i need to soak my probe in vinegar and re calibrate. The probes are both new, but not calibrated since they where new two months ago.

[BrokeColoReefer]

Also, i kind of let the co2 rip since i have it on the controller, in no way have i counted bubbles or drips. The bubbles are in the 120 range and the drip is a constant stream. Over time, i have adjusted it based on water testing in the display. Also i have the 2nd output port open a bit to bleed off the excess co2.

[jlinzmaier]

The probes are both new, but not calibrated since they where new two months ago.

Even brand new probes need to be calibrated before use.

Jeremy

[BrokeColoReefer]

im sorry, i was not clear. I calibrated the neptune with 7/10 and the aquamedic computer with 4/7 when they where new. I have not had a chance yet to mess with them, i will tomorrow and report back. Thanks for everyones help.

[TurboRobert]

If the CO2 stays on long enough the PH will drop drastically. It states in my reactor manual that if you go below 6.0 ph in the chamber the media will break down too fast and turn to a mush state and may clog the reactor. I would adjust the controller back up to 6.5 and re-tune your reactor. You don't want to dissolve the media into mush. I would also start the effluent rate at around 50-60 ml per min not 250ml per min. Even though you have a controller I would move that bubble rate down to around 90 per minute. Too much CO2 to fast is also a problem that can lead to excess CO2 into your tank that is bad for you system.

[jdieck]

<a href=showthread.php?s=&postid=13058177#post13058177 target=_blank>Originally posted</a> by BrokeColoReefer
OK i went down to check the rate, its in the neighborhood of 250 mL/min, not 400. The ph probe in the reactor is reading 5.98. I checked it against the ph probe for the tank, the tank pH probe reads 6.12, so at the very least i need to soak my probe in vinegar and re calibrate. The probes are both new, but not calibrated since they where new two months ago.

Some areas to look for:

a) What is your low setting in the aqua medic? TO have a PH of 5.98 you shall have the set point below 6.0 if you do not (say your set point is at 6.5) then probably the control range is in high so the solenoid will not turn off when the PH drops.
Insure your aquamedic range of control direction is set to low as indicated by the low LED light turned ON.

If your set point is below 6 then increase it to 6.4, maintaining a low PH in the reactor in your case might be possible because you do not have enough retention time of the water to be in contact with the media to have an effective dissolution and PH rising effect. As a result your effluent has a high content of carbonic acid and little bicarbonate.
Note that at a PH of 6 the alkalinity in the effluent will be around 75 to 80% carbonic acid and only 20 to 25% bicarbonate while at 6.3 it will be about 50/50 and at around 6.4 to 6.5 you will have around 60% bicarbonate

b) At 250 ml/min your effluent is still high enough not to have retention time (See above paragraph) You may try to lower it to 100 ml/min and see how it goes; this level combined with a PH set point range at 6.4 to 6.45 the reactor shall provide the alkalinity our system requires.

c) Insure your hysteresis (range of control) is set around 0.05 so the solenoid shuts OFF at the set point of 6.4 and ON at the 6.45 level given by the hysteresis adjustment.

You may notice that the solenoid may switch on and off too often and shuts OFF only a few minutes after it has been turned ON. This is an indication that too much CO2 is being added.
Because you should not rely only on the controller, if the controller or solenoid fails to close and the CO2 rate is too high you may have a PH crash in your system so if switching is too often try closing the CO2 rate a bit at a time until it takes at least around an hour for the solenoid to be turned off when the PH is dropping from the high hysteresis to the low set point. Ideally you want it to be several hours between switchings.

This way if the solenoid fails to close the PH although dropping below the set point it will not drop fast or far enough to be a problem.

d) if you have a large accumulation of CO2 bubbles on top of the chamber with the second output closed (top of the chamber), then the CO2 might not be dissolving properly and your recirculation has been reduced by mud plugging the media or supporting sponge. You may need to rinse the media and the sponge more often to remove the muddy residue.

Some small accumulation is usually OK although may build up to the point were your recirculation pump looses priming. To prevent this you may close outlet 1 and switch your effluent line to use outlet 2, that way any small bubbles will be carried out of the reactor and the pump will not loose priming.

e) Finally, measure the alkalinity of the effluent, if lower than 20 dKh your effluent is still too high or your media is so plugged that there is little or no recirculation.