Setting up Kalkwasser for 3,000 gallon tank

[MrMarth]

Hey Everyone,
I would like to set up a Kalkwasser system for our 3,000 gallon reef tank. Overall, the tank has very stable chemistry other than pH (which I expect is due to elevated CO2 from the calcium reactor).

Does anyone have any recommendations on reactors/setups for a tank this size? Thanks!

Tank Parameters:
pH: 8.10-8.15 (would like 8.20-8.30)
Salinity: 35 ppt
Ammonia-N: 0 ppm
Nitrite-N: 0.005 ppm
Nitrate-N: 0.5 ppm
Alkalinity: 225 ppm CaCO3
Calcium: 440-450 ppm
Magnesium: 1390-1400 ppm

Additional Media/reactors:
Carbon
GFO
Calcium Reactor
Ozone currently offline

 

[dave.m]

What kind of calcium reactor are you using? If it doesn't have a twin tower design may I suggest you consider adding one? That would help with the uneven CO2 levels. Maybe a Kalk reactor wouldn't be necessary. They are certainly messy things to add.

Dave.M

 

[wiseman79]

I've always disliked Kalk and the reactors were always troublesome. I left them behind. Maybe CO2 absorption media instead? What benefits are you looking for from the higher PH?

 

[MrMarth]

What kind of calcium reactor are you using? If it doesn't have a twin tower design may I suggest you consider adding one? That would help with the uneven CO2 levels. Maybe a Kalk reactor wouldn't be necessary. They are certainly messy things to add.

Dave.M

The exact model is escaping me at the moment, but it is a single tower design. I can get the specifics tomorrow.

I've always disliked Kalk and the reactors were always troublesome. I left them behind. Maybe CO2 absorption media instead? What benefits are you looking for from the higher PH?

I don't actually know anything about CO2 absorption media. I will have to look into it.
I'm trying to boost pH, at least for the short term, to get some quick growth out of the tank (increased pH will make calcium carbonate formation easier, if I understand the chemistry correctly). I need it to fill in for the next 6-12 months, then I can shift to maintenance.
I maintain the Magnesium, Calcium, and alkalinity through supplemental dosing of 7:1 Magnesium Chloride + Magnesium Sulfate, Calcium Chloride, and Sodium Carbonate based on measured parameters a couple times a week. If I can reduce the supplemental dosing and solve my CO2 issue at the same time, I'd like to go with the Kalkwasser. My plan was to add a measured dose to a container each day (to prevent overdosing and hardening at the bottom of the container) and have it hooked up to a peristaltic pump (most likely) to dose it over the whole day. If the general consensus is that kalkwasser is more work than it's worth, I will look for other options (like CO2 absorption media).

 

[dave.m]

Sounds like you are chasing numbers instead of going by the health of your tank. There is no set point for pH any more than there is for the rest of the parameters you have listed. How are your corals doing? Are they growing well? Good colouration?

Dave.M

 

[MrMarth]

The corals are growing slow for the most part (montipora and a couple acros being the exceptions), coloration is mediocre, polyp extension is low. I don't honestly think pH is the issue, I wanted to see if increased pH would be an improvement though. I'm taking this tank over after it's been running for two years under another person's care.

Flow and lighting are both major factors as well, and I will be evaluating them too.

 

[wiseman79]

Honestly, PH is the one thing I don't worry about under general conditions. You'd do better working towards proper levels of Ca, Alk, and Mg, and working to keep them consistent and steady. PH is more of a troubleshooting test for me than it is something I test in order to alter or even maintain it regularly. Here's some CO2 absorption media for example though if you do decide to go that route- BRS Media.

 

[dave.m]

The Ca solution might be as simple as sending the output of your existing calcium reactor through a second reactor of similar size containing more calcium reactor medium.

Dave.M

 

[tmz]

A second coruise of reactor media would add more alkainity as well; not just calcium.

 

[tmz]

Maintaining pH above 7.8 is improtant as coral skelton can beging to dissove at 7.7. I prefer 8.2 to 8.3 for a variety of reasons. Alk needs to reamian constant and any tweaks for pH should avoid bouncing alk around./

 

[MrMarth]

I got the info on the calcium reactor. It is a Korallin C10002 Calcium Reactor with Eheim Pump. We ran into some issues with our lighting system this week so the coral got fairly stressed. So we're going to hold off on making any changes in the near future and give the coral some time to recover before any new changes.

 

[Reefvet]

. If the general consensus is that kalkwasser is more work than it's worth, I will look for other options (like CO2 absorption media).

Look for other options. KW is not a viable method for a tank that size. A supplement to a CR, possibly. Still it's too much work and stability will be evasive.

Maintaining pH above 7.8 is improtant as coral skelton can beging to dissove at 7.7. I prefer 8.2 to 8.3 for a variety of reasons. Alk needs to reamian constant and any tweaks for pH should avoid bouncing alk around./

Coral will be stable right down to 7.79 pH and you'll find no significant change in growth due to alkalinity shift in a tank that drops to that value daily.

I've done research on this for 30+ years.

Here's a running example. No growth issues here. A small tank is being used here because of it's inherent instability.

NSW @ 35
Alk 7 dKh
CA 350
Mag 1250


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