Large tank Ca Reactor--- HELP?!?!

[Tre' Landrum]

I have a large tank (a little over 1000gal total vol)
I have a Reef Octopus SRO 5000-D Dual Calcium Reactor

As of now I only have some fish, and not even very much light on my tank, but it has been set up for over 6 months. (man it takes a lot of time money and effort to bring a tank this big online!!!)

With this little of a load (esp load that is using up Ca) I am kinda surprised to be using up as much Alkalinity as I am.

I used Soda Ash to bring the Alk up to 9 (higher than I really wanted it, but it works, and is better than the <5 that it was)

I have my CaRx with controls took keep the pH between 6.6-6.8,
I started with 25ml/h, am now up to 75ml/h.
My alk is now in the upper 6's

This just seems to be a lot more that I was expecting with as little as I have in my tanks. Sure when I have the lights on, corals growing, and lots of things needing Ca, but with nothing in there why is the Alk drooping still? Am I doing something wrong with my Ca reactor!?!?

 

[mitch91175]

Are you running any GFO in the tank?

 

[Tre' Landrum]

Are you running any GFO in the tank?

No

 

[mitch91175]

Tank shots

 

[mitch91175]

Being setup for 6 months you likely do not have much coralline algae in there. If you do that still doesn't explain the drop so quickly without have a massive amount of SPS. Have you tested with a different test kit just to make sure that you are correct? Also have you tested the effluent dKH? What type of media are you using? Has the pH probe been calibrated properly and functioning properly?

By increasing the rate from my understanding about CaRx, you are actually decreasing the potency of the effluent. I would think that maybe dropping the pH in the chamber even lower would help if you want to keep that flow rate. But you have to consider the media that you have and it's low melting point. You do not want a bunch of mush.

 

[Tre' Landrum]

Being setup for 6 months you likely do not have much coralline algae in there. If you do that still doesn't explain the drop so quickly without have a massive amount of SPS. Have you tested with a different test kit just to make sure that you are correct? Also have you tested the effluent dKH? What type of media are you using? Has the pH probe been calibrated properly and functioning properly?

By increasing the rate from my understanding about CaRx, you are actually decreasing the potency of the effluent. I would think that maybe dropping the pH in the chamber even lower would help if you want to keep that flow rate. But you have to consider the media that you have and it's low melting point. You do not want a bunch of mush.

A friend has encouraged me to drop it, and after watching some BRS investigates I think I will some. It is currently 6.6-6.8, I am thinking moving it to 6.4-6.6 wont drop it too much, and I will turn down the flow back to 25 or so. Then retest.

 

[jda]

Stop using the pH probe and a controller, learn how to tune the thing by hand using effluent dKh and it will keep up with the demand. If you want to learn how to do this, I can teach you. You will have to get here eventually since this steady production method is the only way to keep up with high demand. Let me know. If you still want to use a probe and controller, then I will bow out... and good luck.

 

[mitch91175]

Stop using the pH probe and a controller, learn how to tune the thing by hand using effluent dKh and it will keep up with the demand. If you want to learn how to do this, I can teach you. You will have to get here eventually since this steady production method is the only way to keep up with high demand. Let me know. If you still want to use a probe and controller, then I will bow out... and good luck.

Good advice @jda. Wouldn't knowing both methods help him out even further along? If he understand measuring his effluent dKH he can see where the pH in the chamber is and manage with it as well. Am I confused about that cause always wanting to learn and get different insight.

 

[jda]

You want the effluent dKh to be a result of consistent effluent rate and bubble count, not the up/down nature of using a pH probe with periods of dumping co2 and then periods with it being off. The most consistent and reliable CaRx, IMO, is one that only uses a pH probe to alert if the pH is out of range, but does not do anything to the co2. I stopped using a pH probe in my reactors more than a decade ago when I figured out that most of the time they were a problem and not the reactor. The pH probe does nothing for me.

 

[mitch91175]

You want the effluent dKh to be a result of consistent effluent rate and bubble count, not the up/down nature of using a pH probe with periods of dumping co2 and then periods with it being off. The most consistent and reliable CaRx, IMO, is one that only uses a pH probe to alert if the pH is out of range, but does not do anything to the co2. I stopped using a pH probe in my reactors more than a decade ago when I figured out that most of the time they were a problem and not the reactor. The pH probe does nothing for me.

So you really have to know your dKH consumption well in order to get it fine tuned to that point. Guess you can always start low bubble count then increase from there. I just use my pH probe and have a consistent effluent and everything works our really well. Haven't run into any issues. I do dose dKH when needed with the Alkatronic.

Heck I am even dosing kalk. Helps keep my pH above 8.1. Noticing good growth, but no where near you yet @jda,

 

[Rick.45cal]

You should only make singular adjustments when tuning a reactor. Lowering the pH in the reactor and lowering the effluent rate at the same time is counterproductive. You have a very large system and 75ml a min might not even be enough to keep up. If I were you, I’d lower the pH in the reactor and leave the effluent rate alone. Wait for the system to stabilize and decide where to make the next adjustment. In a big system like yours it may take several days or a week for a tiny change to fully make an impact. I also agree with jda, tuning the reactor by hand by limiting the CO2 input to control the output of the reactor is the best way to run a calcium reactor, with a good regulator it’s highly unlikely it can run away from you.

As an example:
A flow rate of 75ml/min equals 108 L/day. In a 3785L (1000g) system, if your corals are using 1 dKh a day that’s 3785 dKh leaving your system every day. For you to attain 3785 dKH increase from your reactor at 108L/day your effluent will have to be +35.04 dKh above what dKh the tank is at. (It helps to know your daily alkalinity consumption).

 

[Tre' Landrum]

Wow, this is why I posted this here... totally taking what I thought how to run a CaRx and doing it totally different!

OK, thank you all... working on it.

 

[jda]

You want to find an effluent output and bubble rate to get your effluent dKh in the mid 20s. Then, you raise or lower BOTH in that same ratio until your tank needs are met. pH does not matter.

 

[ca1ore]

Yup! Those of us that have used CaRx for decades (there are a few) have mostly converged around this approach. Continuous CO2/effluent rate is the best way to run one.