menglish February 16, 2021 Share February 16, 2021 So I have been struggling to keep my alk above 8 dkh for a while now. Decided to add a Kalk stirr to help. At one time was adding upto 2000 mls per day of Kalk water. It is not making a difference. I have a 180 mx reef dt with lots of HUGE SPS colonies. I run a Geo CaRx with 2 chambers. I use Carib sea media and the CaRx chamber ph is set to 6.4 and the effluent is open all the way. Today i decided to test the alk coming out of the reactor and it was only 11 dkh. That number should be about 35 kdh (according to BRS video series). I have calibrated the Reactor ph probe several times, so that is not the issue. I have went through CO2 tank and can see the solenoid opening and closing. The ph is stable in the reactor at 6.5. I dont think i tank is using that much alk. I have been using extra soda ash to bring the ph up as it settles about 7.4 dkh Any suggestions? Link to comment Share on other sites More sharing options...
AlanM February 16, 2021 Share February 16, 2021 does the media in the CaRx seem to get used up? Link to comment Share on other sites More sharing options...
menglish February 16, 2021 Author Share February 16, 2021 Yes, the media is being used up as i have topped in off several times Link to comment Share on other sites More sharing options...
pizzaguy February 16, 2021 Share February 16, 2021 Is the effluent rate so fast that your not giving enough time for the media to melt? I would try to slow the effluent a bit retest the dkh in 24 hours and see where its at. Link to comment Share on other sites More sharing options...
pizzaguy February 16, 2021 Share February 16, 2021 For what its worth, my ph low point on mine is 6.2 because I needed it to melt faster to keep up. I wouldn't do that yet in your case, but try the above first. Reason for that is you say you're set at 6.4 but reactor ph stays at 6.5 That tells me its not enough time do to flow rate. Or if your using a carbon doser valve turn it down a tiny bit to allow more co2 in at a faster rate to get reactor ph down Link to comment Share on other sites More sharing options...
menglish February 16, 2021 Author Share February 16, 2021 Hi Eric, Great suggestion!!! I think you might be on to something there. Did some test just now; -The reactor ph is 6.4 -the flow rate of the effluent (all the way open) is 170mls/min -the alk coming out of that is 12 dkh I will adjust the flow rate down to 50mls/min and retest tomorrow. I am not using a carbon doser, so i cannot adjust the co2 that way, but i can increase the bubble rate a bit to allow more co2 in the chamber. Link to comment Share on other sites More sharing options...
AlanM February 16, 2021 Share February 16, 2021 This seems unlikely, given your profession, but is there a chance that your alk test is off? Do the corals look like they're doing ok or is there a reason you started wanting to raise your alk? Link to comment Share on other sites More sharing options...
pizzaguy February 16, 2021 Share February 16, 2021 I just went through the same thing a few days ago where my ph in reactor was rising. So I turned the co2 up a bit. But a while back I had to go from 6.5 low point to 6.2 low point as I wasn't keeping up either. Basically same exact thing. Tom has taught me a tremendous amount on reactor control. He's brilliant when it comes to this stuff Link to comment Share on other sites More sharing options...
menglish February 16, 2021 Author Share February 16, 2021 So I have been dealing with this for months. I do not think it is an issue of testing. I use a hannah and i have a red sea kit too. As for my corals, all my sps colonies are doing great. I have one that is basket ball size and a few that are volleyball size. I have had problems with my lps. I had a beautiful bubble coral (volleyball size) and it just melted away and i have no idea why. Next to it and touching, is a huge yuma rock, some of the polyps on the yuma are just releasing from the rock. again, have no idea why. They are starting to look better now. Link to comment Share on other sites More sharing options...
menglish February 17, 2021 Author Share February 17, 2021 So here is an update; CaRx chamber pH 6.4 CaRx media. Carib sea Effluent flow rate 50mls/min Effluent Alk 17 dkh This Alk is still much lower that expected. Any other suggestions? Link to comment Share on other sites More sharing options...
WheresTheReef February 17, 2021 Share February 17, 2021 I don’t have any experience with a CaRx, but was wondering if you tried different media? Is this your first time using the setup? If not, how was it working before and did anything change? Link to comment Share on other sites More sharing options...
menglish February 17, 2021 Author Share February 17, 2021 17 minutes ago, WheresTheReef said: I don’t have any experience with a CaRx, but was wondering if you tried different media? Is this your first time using the setup? If not, how was it working before and did anything change? BRS has done these experiments you suggest. Reactor media does make a different. I was comparing my results to what they have done. based on media type, ph and flow rate. Perhaps i can play with the CO2 rate, but that should not matter as much, given you are going by the ph in the reactor Link to comment Share on other sites More sharing options...
pizzaguy February 17, 2021 Share February 17, 2021 What are your high and low set points Link to comment Share on other sites More sharing options...
WheresTheReef February 17, 2021 Share February 17, 2021 35 minutes ago, menglish said: BRS has done these experiments you suggest. Reactor media does make a different. I was comparing my results to what they have done. based on media type, ph and flow rate. Perhaps i can play with the CO2 rate, but that should not matter as much, given you are going by the ph in the reactor If the media makes a difference why not try different media? It wouldn’t go to waste if you can use it. This would tell you if the media itself is the issue. Buy or grab some from a reefing buddy to test. Also, have you tested your Mg and Ca? If you are struggling raising your Alk with multiple methods then it could be another issue. At least you could eliminate that as a possibility. Link to comment Share on other sites More sharing options...
menglish February 17, 2021 Author Share February 17, 2021 I will have to get some Two little fishie media Just test and the tank Mag 1400 Ca 375 Alk 9 (but i added extra soda ash to brink it up from 7.7) Will let it run a few days then will retest Link to comment Share on other sites More sharing options...
WheresTheReef February 17, 2021 Share February 17, 2021 Ok looks like you are able to raise alk and other 2 look good. Just be care about fluctuating alk too much at a time while you are working things out. Link to comment Share on other sites More sharing options...
thakki February 17, 2021 Share February 17, 2021 (edited) I had similar problem sometime back...I just had to dial down ph to 6.50 and at 30 ml/min it maintains ALK at 8.5 on an average. I am using TLF Reborn and the tank water volume is close to 200 gal. I also drip Kalk to keep up with pH thats probably adding to the ALK a bit too. I never ran the feed pump higher than 30 ml..makes sense to keep one variable constant and dial the other which is the pH...I would start from 20 ml/min and test the effluents alkalinity. Edited February 17, 2021 by thakki Link to comment Share on other sites More sharing options...
menglish February 17, 2021 Author Share February 17, 2021 This has been an issue for a long time. I was using a CaRx, Kalk Stirr and soda ash to get the alk up. The alk would dip to 7.4dkh. I did noticed that my Mg was low (1200). So perhaps that had something to do with it. I was concerned that the Alk was precipitating out of solution. I have since brought it up over time. I will continue to watch it over the next few days. Would also get some TLF Reborn media. Perhaps that would make a difference Link to comment Share on other sites More sharing options...
Origami February 18, 2021 Share February 18, 2021 Milton, are you really confident that the pH probe in your reactor is reading correctly? Is the circulating pump in your reactor working and keeping the acidified water evenly mixed? You need dissolution of the CO2 (solvent acidification), solvent dispersion (mixing), contact time (flow rate control), and low (controlled) solvent pH and decent media to get a decent boost from the reactor. You don't always need to hit 35 dKH in the effluent but it should be higher than 11 dKH. The basic formula's going to look something like this: net_alk_dosed (meq) = (effluent_alk_concentration (meq/ml) - tank_alk_concentration (meq/ml)) x flow rate (ml/s) x time (s) So you can compensate for low concentration with added flow or longer dosing time. But, when your net alk boost is low, then you end up running the pump continuously and may find it difficult to keep up with consumption. Low magnesium reduces the supersaturating calcium, facilitating abiotic precipitation in your tank. Because you're having low pH problems in the tank but not getting much concentration, I'm curious as to whether or not you're getting good dispersion of the solvent in the reactor. By any chance, is the media clogged or channeling the flow inside the reactor? Link to comment Share on other sites More sharing options...
menglish February 18, 2021 Author Share February 18, 2021 Hi Tom, Yes, I am confident all the equipment are working correctly. I tested the ph probe, that is fine. Check all the pumps, that is fine, I can hear the solenoid coming on and off. I can see the CO2 bubbles in the bubble chamber. Media is definitely being used up and the reactor ph is stable between 6.37-6.43. (it is set If CaRxpH > 6.40 Then ON If CaRxpH < 6.30 Then OFF) Rechecked the effluent today and it is stable at 17 dkh ( over two days). I was still thinking this is a bit low Alk is down a bit from 9 (yesterday) to 8.6 ( this morning) flow rate is still 50 mls/min Link to comment Share on other sites More sharing options...
Origami February 19, 2021 Share February 19, 2021 Milton, try turning off the effluent flow and letting the circulation pump run for a half hour or so and check the effluent concentration again after the media has had more time to dissolve. What size Caribsea media are you using? I'm assuming it's the coarse stuff and not the fine stuff. Link to comment Share on other sites More sharing options...
Origami February 19, 2021 Share February 19, 2021 The previous test is just to figure out if your reactor pH is leading to saturation at that level. You may have to dial the reactor pH down just a little, too. But, I've got to say, I run mine really close to yours: 6.33 to 6.40. But, unlike yours, I only run for 18 minutes an hour at 80 ml/min feed rate. I've not checked effluent concentration in a long while, though. If you're running your reactor now at 50 ml/min continuously, you're dosing 3L/hr of effluent at just under 6.1 meq/liter. Some brands of media have been known to dissolve a little differently than other brands. I guess that this variation can occur within a brand, too, over years as sources vary. When I first started using a calcium reactor (over ten years ago), I used an effluent-drip method of dosing. Back then, the effluent concentration was something like 33 dKH as I recall. However, the little microvalve would always clog up and control was impossible. So I increased the rate to a steady stream and raised the pH in the reactor. Over time, I migrated to lowering the pH to raise the concentration in the reactor (but probably considerably less than the 33 dKH from long ago), and used a peristaltic feed pump running on a programmable duty cycle under Apex control. This gave me a means of dialing in the required dosage fairly quickly by taking two or three measurements over a few days. Link to comment Share on other sites More sharing options...
menglish February 20, 2021 Author Share February 20, 2021 So i turned off the reactor feed pump for a few hrs and the ph in the reactor increased from6.4 to 6.63. I measured the Alk coming out before and after the change and it went from 17dkh to 16dkh. Not a big change. the tank alk dropped from 8.6 yesterday to 7.8 dkh today I will try lowering the reactor ph from 6.4 to 6.2 and see what that does Link to comment Share on other sites More sharing options...
pizzaguy February 20, 2021 Share February 20, 2021 Now I'm definitely lost. You turned the feed pump off and the ph in reactor went up ?? Link to comment Share on other sites More sharing options...
menglish February 20, 2021 Author Share February 20, 2021 That so does not make sense. You would expect the ph in the chamber to increase. However, since no flow going our of the reactor, i can see this happening. I am using a small Eheim pump for the feed. I know it was off as the flow out of the reactor stopped. I know the circulation pump was still on and working as i can hear it put see some bubbles coming up in the reactor Link to comment Share on other sites More sharing options...
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