Calcium reactor issue (pH fluctuation)

[Lennon's Reef]

I have an AquaMaxx cTech T-NANO hang-on calcium reactor. I just set it up on my 11-gallon aquarium because I recently got my first stony coral frags and want to start maintaining proper chemistry for these corals.

I’m using a Versa peristaltic dosing pump from EcoTech Marine to dose the effluent. The pH controller I’m using is the MC122 from Milwaukee, and the probe itself is the double-junction one made by Neptune. I have the MA957 CO2 regulator from Milwaukee.

I’m running into an issue where the pH in the reactor fluctuates rapidly between 6.5 and 6.7 while the Versa is on. I assume the higher pH tank water being drawn into the reactor is causing this problem. When I turn the Versa off the reactor’s pH is rock steady. I can run the Versa at a rate of 1ml/min without issue, but any drip rate higher than that causes the whole system to go haywire. The fluctuating pH causes the controller to cycle the solenoid on my CO2 regulator on and off over 20 times per minute. At that rate I’ll need a new regulator by next month! ;Nailbiting

I can run the reactor at a low drip rate for now, but eventually I worry I won’t be able to keep up with a tank full of stony corals. I’d like to figure out how to resolve the issue now rather than later.

thanks in advance for any advice!

 

[Sisterlimonpot]

11 gallon tank with 1 coral doesn't have a big enough demand for a CaRx. If you're adamant about having a CaRx I'd suggest raising the pH up to 7 and test KH daily to fine tune your reactor. It's quite possible that you don't need your versa running more that 1ml/min.

You're observation is right on par for what to expect with the CaRx, the only thing is that you don't want it triggering the solenoid constantly. As demand goes up you will see the pH stabilize a bit more and you can start increasing the versa.

 

[kevin_e]

I can't help with the pH issue, but here's a bump for someone that may be able to. The versa...is it made for continuous duty and do you use it as such? I would also be concerned about the reactor lowing the pH in your tank since it is so small.

Curious though- you have one acro frag in an 11 gallon tank and you are running a calcium reactor? I can't help but think you will have significant changes in calcium and alkalinity from dosing very soon. The demand can't warrant a reactor. I'd imagine water changes would be sufficient for a very long time.

 

[shadesatsetbreak]

imo no need for a carx on a tank that small. Is 11 gallons your total system volume? Do you have a sump that adds more? Otherwise, you'll be producing nitrates quick enough that you have to do frequent water changes anyways.

 

[Lennon's Reef]

I can't help with the pH issue, but here's a bump for someone that may be able to. The versa...is it made for continuous duty and do you use it as such? I would also be concerned about the reactor lowing the pH in your tank since it is so small.

Curious though- you have one acro frag in an 11 gallon tank and you are running a calcium reactor? I can't help but think you will have significant changes in calcium and alkalinity from dosing very soon. The demand can't warrant a reactor. I'd imagine water changes would be sufficient for a very long time.

Thanks for the bump!

Yes, the Versa was designed to be a continuous duty pump and I do use it as such. It is currently set at a constant rate of 1mL/min. (I went with the Versa over the one made by Kamoer because of the Versa’s much smaller dimensions).

I haven’t run into issues with my pH yet, but I will be on the lookout for that. My pH before the rector came online was around 8.1 and it seems to hover around 8.0 now. I do use soda lime on the air intake of my skimmer to bump the pH up. My calcium before using the reactor was 362 ppm and alkalinity was 5.5 dKH. Now after two days of steady 1mL/min dripping it’s up to 383 ppm calcium and 6.4 dKH. To me that seems like a VERY slow increase considering I don’t have much coral in the tank at all yet. And if that’s the upper limit of how much effluent as I can push through the reactor then you can see why I’m worried that it won’t scale when I have larger colonies.

The total actual water volume including sump is roughly 11 gallons. I know it’s small, but I do plan to fill it out with a lot of SPS. I thought running a calcium reactor would be simpler than dosing two-part and having to worry about trace elements. I came over from the freshwater side of things so using CO2 also felt comfortable.

Oh and I should mention that my calcium and alkalinity measurements were made with Hanna checkers, and that I use Tropic Marin pro reef salt

 

[Lennon's Reef]

imo no need for a carx on a tank that small. Is 11 gallons your total system volume? Do you have a sump that adds more? Otherwise, you'll be producing nitrates quick enough that you have to do frequent water changes anyways.

Thanks for the reply!

Yes 11 gallons is all I’ve got, including sump. I’m sure I could do water changes to keep levels where they need to be, but my goal for this system was to keep water changes to an absolute bare minimum.

Nutrient removal is being handled by my ZEOvit reactor and skimmer to great effect

Contaminants and pollutants are removed with activated carbon

The last piece of the no-water-change puzzle was the water chemistry, and the carx seemed like the best solution to me because I wouldn’t have to worry as much about trace elements (those could be handled with VERY infrequent water changes), and calcium & alkalinity are added in the correct ratio.

 

[Lennon's Reef]

11 gallon tank with 1 coral doesn't have a big enough demand for a CaRx. If you're adamant about having a CaRx I'd suggest raising the pH up to 7 and test KH daily to fine tune your reactor. It's quite possible that you don't need your versa running more that 1ml/min.

You're observation is right on par for what to expect with the CaRx, the only thing is that you don't want it triggering the solenoid constantly. As demand goes up you will see the pH stabilize a bit more and you can start increasing the versa.

Thanks for your reply!

I know the CaRx isn’t needed for my current demand, but I think it can be a good solution for a high-demand SPS aquarium (albeit only 11 gallons) which I hope my little tank will be some day. The calcium reactor was simply more appealing to me than going the dosing route.

In order to give the reactor a test run (and also because I don’t have any two part solution) I decided to try to use it to raise my levels of calcium and alkalinity from 362 ppm and 5.5 dKH respectively to more reef-tank-appropriate levels. In doing so I discovered the limit of how much effluent I can push through the reactor without my solenoid going haywire. I was able to raise calcium from 362 ppm to 383 ppm and alkalinity from 5.5 dKH to 6.4 dKH with 48 hours of 1mL/min dripping while the reactor sat at a pH of 6.5. (Oh and I’m using Reborn media by the way).

I feel like if it took two days to raise the levels by that small margin when I have almost no coral in the tank then the CaRx won’t be a viable option for a high-demand tank unless I can figure out a way to push more effluent/min out of it. But as of now I see now way to do that because of the pH fluctuation issue.

Maybe I’ll have to run the reactor at a super low pH when the drip rate can’t keep pace with the demand?

 

[dank reefer]

You can gradually raise your effluent ML (say to 5ML) and then adjust your PH in the Carx to your desired amount. Your PH might also be fluctuating as the PH in the tank rises and falls too.

 

[Lennon's Reef]

You can gradually raise your effluent ML (say to 5ML) and then adjust your PH in the Carx to your desired amount. Your PH might also be fluctuating as the PH in the tank rises and falls too.

Thanks for the reply!

I can’t raise the drip rate without causing the system to go crazy. Even if I raise the drip rate to 1.5mL/min the pH in the reactor starts to oscillate between 6.5 and 6.7 over and over at 20-25 times per minute.

Do you mean that I should raise the pH in the reactor, turn up the drip rate, and then try lowering the pH in the reactor back down? I don’t really see how that could fix the issue but I’m more than willing to try it out!

That’s interesting what you said though about the reactor pH fluctuating because the tank pH is fluctuating... I’m not sure it matters, but I do have the effluent dripping into the sump BEFORE the intake line going to my Versa. The effluent drips into my chaeto chamber which then flows into my return chamber. The Versa intake line is right in front of my return pump in that chamber. Could the low pH of the effluent be causing the pH of the return chamber to fluctuate so that when the Versa draws water from that chamber it causes the CaRx pH to fluctuate? I was assuming the tiny amount of effluent wouldn’t significantly affect the pH of my sump but I could be wrong on that. I think I’ll try moving the intake upstream of where the effluent drips out and see what happens.

 

[dank reefer]

Thanks for the reply!

I can’t raise the drip rate without causing the system to go crazy. Even if I raise the drip rate to 1.5mL/min the pH in the reactor starts to oscillate between 6.5 and 6.7 over and over at 20-25 times per minute.

Do you mean that I should raise the pH in the reactor, turn up the drip rate, and then try lowering the pH in the reactor back down? I don’t really see how that could fix the issue but I’m more than willing to try it out!

That’s interesting what you said though about the reactor pH fluctuating because the tank pH is fluctuating... I’m not sure it matters, but I do have the effluent dripping into the sump BEFORE the intake line going to my Versa. The effluent drips into my chaeto chamber which then flows into my return chamber. The Versa intake line is right in front of my return pump in that chamber. Could the low pH of the effluent be causing the pH of the return chamber to fluctuate so that when the Versa draws water from that chamber it causes the CaRx pH to fluctuate? I was assuming the tiny amount of effluent wouldn’t significantly affect the pH of my sump but I could be wrong on that. I think I’ll try moving the intake upstream of where the effluent drips out and see what happens.

I am not a Guru on CARX, but you might want to move the effluent line into your return chamber.

If you turn up your drip rate, and not mess with PH in reactor, the PH should rise. Once it rises, you want to test your effluent and see what you get. @jda recommends your effluent to be around 20-21 DKH as a base line, and then adjust.

My PH Fluctuates in my CARX all the time when my tank ph raises and falls, and my alk stays between 8.1-8.5 from what my Trident, and Salifert test kits report.

Here is a graph on the APEX and you'll see the rise and fall of Tank PH, and CARX PH. I keep my PH in the CARX high as that is what seems to work for my tank consumption for right now. Total water volume on my tank is around 160g of water and I drip 80ml a minute.

Orange graph is CARX PH
Blue is Tank PH

 

[ReefGeezer]

Slow the CO2 addition (Bubble Count) to the point your pH inside the reactor is stable WITHOUT the controller going off. Since your demand is low, set the pH slightly above that recommended for the media you are using.

Don't use the reactor to raise alk or calcium. Use two-part additives to do that. The calcium reactor should the be adjusted until it just maintains the level.

Adjusting, referred to "dialing-in", consists of changing the effluent rate and bubble count in small increments until the reactor maintains the required alkalinity. Increasing the effluent initially raises alkalinity in the DT but also raises pH in the reactor. Raising the bubble count lowers pH which increases alkalinity of the effluent. So...

Step 1: Establish pH inside the reactor at a level higher than the media manufacturer recommends... Maybe 6.8 to 7. Adjust the needle valve so the pH is maintained WITHOUT the solenoid closing. Set the controller so the solenoid closes if the pH drops .1 or .2 less than the level you established.

Step 2: Start a minimal effluent flow through the reactor. Sounds like that might be 1ml/min for your tank. Adjust the CO@ level again to keep pH stable at the required level.

Step 3: Dial in the effluent rate that keeps Alk stable. Don't worry about calcium right now. Test alk... If Alk is high slow the effluent rate and then adjust the bubble count so pH in the reactor doesn't rise. If alk is low increase the effluent and adjust the bibble count to keep the pH at the desired level. Don't forget to reset the controller level if needed. This will take a while. Be patient. Once you find the sweet spot, you shouldn't have to mess with it much.

If the minimum effluent rate raises alkalinity, increase the pH inside the reactor so the media dissolves slower. That'll reduce the alkalinity of the effluent. In your little system with so little demand, you could be looking at running the pH on the high side for quite a while... like 7.5 or higher even.

 

[Lennon's Reef]

Slow the CO2 addition (Bubble Count) to the point your pH inside the reactor is stable WITHOUT the controller going off. Since your demand is low, set the pH slightly above that recommended for the media you are using.

Don't use the reactor to raise alk or calcium. Use two-part additives to do that. The calcium reactor should the be adjusted until it just maintains the level.

Adjusting, referred to "dialing-in", consists of changing the effluent rate and bubble count in small increments until the reactor maintains the required alkalinity. Increasing the effluent initially raises alkalinity in the DT but also raises pH in the reactor. Raising the bubble count lowers pH which increases alkalinity of the effluent. So...

Step 1: Establish pH inside the reactor at a level higher than the media manufacturer recommends... Maybe 6.8 to 7. Adjust the needle valve so the pH is maintained WITHOUT the solenoid closing. Set the controller so the solenoid closes if the pH drops .1 or .2 less than the level you established.

Step 2: Start a minimal effluent flow through the reactor. Sounds like that might be 1ml/min for your tank. Adjust the CO@ level again to keep pH stable at the required level.

Step 3: Dial in the effluent rate that keeps Alk stable. Don't worry about calcium right now. Test alk... If Alk is high slow the effluent rate and then adjust the bubble count so pH in the reactor doesn't rise. If alk is low increase the effluent and adjust the bibble count to keep the pH at the desired level. Don't forget to reset the controller level if needed. This will take a while. Be patient. Once you find the sweet spot, you shouldn't have to mess with it much.

If the minimum effluent rate raises alkalinity, increase the pH inside the reactor so the media dissolves slower. That'll reduce the alkalinity of the effluent. In your little system with so little demand, you could be looking at running the pH on the high side for quite a while... like 7.5 or higher even.

I am not a Guru on CARX, but you might want to move the effluent line into your return chamber.

If you turn up your drip rate, and not mess with PH in reactor, the PH should rise. Once it rises, you want to test your effluent and see what you get. @jda recommends your effluent to be around 20-21 DKH as a base line, and then adjust.

My PH Fluctuates in my CARX all the time when my tank ph raises and falls, and my alk stays between 8.1-8.5 from what my Trident, and Salifert test kits report.

Here is a graph on the APEX and you'll see the rise and fall of Tank PH, and CARX PH. I keep my PH in the CARX high as that is what seems to work for my tank consumption for right now. Total water volume on my tank is around 160g of water and I drip 80ml a minute.

Orange graph is CARX PH
Blue is Tank PH

Thank you both for your comprehensive responses!

I didn’t realize the pH controller is only meant to act as a backup for if the pH in the reactor gets too low. I will try to balance the bubble count and effluent drip rate to the point where the controller almost never closes the solenoid.

I know I should be using two part to raise the calcium and alkalinity to proper levels, but I don’t have any on hand, and since shipping is so delayed right now I figured using the CaRx is currently my best option for getting the levels up. Once I reach proper levels I’ll follow the steps ReefGeezer laid out to maintain them.

There really is no issue at the moment since I’m successfully raising my levels -even at my slow 1mL/min drip rate- and I’m sure I can maintain proper chemistry once I reach it by dialing the reactor back. My main concern was that the CaRx would not be able to keep pace with a fully stocked reef tank a year or two down the road if I can’t increase my drip rate from 1mL/min. I attached a graph of my levels over the past few days. My reactor is at a pH of 6.5. I was worried because I felt like the rate of increase in my levels is very slow -considering my tank has almost no coral. And that if the reactor can only be run at a max of 1mL/min, then it would be quickly outpaced by demand when my tank is fully stocked.

Assuming my reactor is eventually outpaced and I do have to turn the drip rate up, if the pH fluctuates rapidly between 6.5 and 6.7 even when bubble rate is balanced with drip rate, would I just set the controller to close the solenoid at a pH of 6.4 then? If so, I worry that the pH would continue to fluctuate and make the solenoid go crazy by hitting 6.4 repeatedly. I suppose I could turn the drip rate up high enough to prevent it from ever hitting 6.4? In that case should I even bother with a pH controller?

I think for now I’ll focus on dialing the reactor in once my levels get to where they need to be and see how well it keeps pace over time.

 

[ReefGeezer]

When the reactor fails to keep up, you simply adjust it... more effluent and more CO2 as needed.. About any calcium reactor has the capacity to keep up with huge demands regardless of size. Smaller ones just need media replacement more often.

 

[dank reefer]

I only monitor my PH in the reactor and my carbon doser runs 24/7. I do not use a ph controller to shut on/off my solenoid.

 

[Lennon's Reef]

When the reactor fails to keep up, you simply adjust it... more effluent and more CO2 as needed.. About any calcium reactor has the capacity to keep up with huge demands regardless of size. Smaller ones just need media replacement more often.

I only monitor my PH in the reactor and my carbon doser runs 24/7. I do not use a ph controller to shut on/off my solenoid.

I took a video of what happens when I turn the drip rate on the Versa from 1mL/min to 2mL/min just so you can see what the issue is. You can hear the solenoid clicking on and off over-and-over as the pH in the reactor fluctuates like crazy. I only have this issue when the drip rate is higher than 1mL/min. The reason I worry is because I feel that some day I’ll NEED to turn it up higher than that, but I won’t be able to. My bubble count is currently pretty low by the way, it’s at 1/4BPS.

 

[dank reefer]

What is your bubble count? 1 bubble every 1-10 seconds?

 

[ReefGeezer]

I took a video of what happens when I turn the drip rate on the Versa from 1mL/min to 2mL/min just so you can see what the issue is. You can hear the solenoid clicking on and off over-and-over as the pH in the reactor fluctuates like crazy. I only have this issue when the drip rate is higher than 1mL/min. The reason I worry is because I feel that some day I’ll NEED to turn it up higher than that, but I won’t be able to. My bubble count is currently pretty low by the way, it’s at 1/4BPS.

So that's 1 bubble every 4 seconds or 15 per minute? To run my low to moderate demand 90 gallon I only have about 35 bubbles per minute @ maybe 10-15 psi of pressure. What is your pressure set at? That makes a difference. More pressure means bigger bubbles so more CO2 per bubble.

Your controller is chattering open and closed because it can't control the CO2 finely enough. Plug the solenoid into the wall and use the pH probe as a monitor to adjust the pH in the reactor with effluent running at 1 ml/min. I'd start the pH at about 6.9 to 7. Then start dialing it in as above.

 

[Lennon's Reef]

What is your bubble count? 1 bubble every 1-10 seconds?

When the reactor fails to keep up, you simply adjust it... more effluent and more CO2 as needed.. About any calcium reactor has the capacity to keep up with huge demands regardless of size. Smaller ones just need media replacement more often.

The video wouldn't open so I converted it to an MP4. Hopefully it works now. My bubble count is one bubble every 4 seconds.

 

[Lennon's Reef]

So that's 1 bubble every 4 seconds or 15 per minute? To run my low to moderate demand 90 gallon I only have about 35 bubbles per minute @ maybe 10-15 psi of pressure. What is your pressure set at? That makes a difference. More pressure means bigger bubbles so more CO2 per bubble.

Your controller is chattering open and closed because it can't control the CO2 finely enough. Plug the solenoid into the wall and use the pH probe as a monitor to adjust the pH in the reactor with effluent running at 1 ml/min. I'd start the pH at about 6.9 to 7. Then start dialing it in as above.

My pressure is at 10 psi. So is my bubble count too high? I’ll try dialing it down. I’d like to keep the pH in the reactor at 6.5 though because I tested the alkalinity of my effluent and it’s at 20.0 dKH which @Jose Esteves recommended.

 

[waterskiguy]

Try to slow the bubble rate down. The only reason it would be shutting off rapidly, like that, would be to turn it off because the PH is too high. 4spb is pretty high to keep ph up at 1mL / min. I have large reactor on my 260 gallon tank and it's only at 1.5spb to keep the ph at 6.1 with a 23mL flow rate. This would be my assumption, form my limited experience. every time mine starts shutting off, like that, its because I have my bubble rate too high.