thoughts on simple kalk reactor

[ctreefer]

I'm in the process of finalizing my plans for kalk dosing and am wondering if anyone has any thoughts on the system I have in mind. I've seen a couple threads with people planning this system, but haven't found one where they've actually run it and its capabilities.

I'm planning on a simplified kalk reactor being supplied with RO water from a doser. The reactor consists of a rodi canister which I'll load with kalk and the water flow will move through the kalk slowly (1 drip per second) and then out the output to the sump. My concerns are will this lead to a saturated solution on the output? I'm trying to create a constant drip with a known solution and would like to keep it simple.

Just curious on Randy's or anyone else's thoughts or if anyone has tried anything similar.

thanks

 

[Randy Holmes-Farley]

Are you going to stir it at all? If not, I doubt you can keep it saturated, but I've not done it that way.

 

[ctreefer]

Randy,

No, I wasn't going to stir it. I think I might give it a try though. Perhaps if I were to make the container larger for more surface area between the water and the kalk this would help. My hope was that since the flow would be so slow that it would give the kalk the time needed to disolve without any action.

Just to check, a saturated solution has a pH of about 12, correct?

 

[Randy Holmes-Farley]

pH is not a very sensitive way to judge saturation, but it can be done. Conductivity is a better way.

Anyway, the pH of saturated limewater is very temperature dependent, but at 25 deg C is 12.45

A drop of 0.3 pH units is a drop in potency of about 50%. A drop of 0.1 pH unit is about 21% (0.2 units is 37%). The best way to do it carefully is to make a for sure saturated solution (say, 1 teaspoon lime in a cup of water), and mesure the pH. Then see how much lower the effluent is, rather than any absolute pH value which will be very prone to error.

One likely problem is the buildup of insoluble claicum carbonate solids on top of the lime, preventing dissolution of the lime.

 

[ctreefer]

OK, good to know. I've been looking at EC meters online. Do these measure alkalinity? What should I be looking for if I'd like to buy one?

thanks again,

vince

 

[Randy Holmes-Farley]

EC meters? You mean conductivity? They measure total ions in solution.

To measure limewater potency, you need one that can measure in the 0-11 mS/cm range (saturated limewater is around 10.3 mS/cm), like the Pinpoint Electronic Salinity meter.

 

[ctreefer]

Randy, I checked out at marine depot their meters and I'm a little confused. You mention salinity meter which they have listed for testing salinity in a salt water system, but they also have a conductivity meter, that measures fresh water hardness.

Which is the right one?

thanks

vince

 

[Randy Holmes-Farley]

It is a confusing issue, largely because of the way companies market them. What you want is a conductivity meter than can read up to 11 mS/cm. Unfortunately, many "conductivity" meters sold to aquarists (often called TDS meters) are confined to low conductivity range, and do not get high enough for limewater potency or tank salinity.

The Pinpoint Salinity meter is really a conductivity meter than can read the higher end of the range, and can measure tank salinity and limewater potency.

I have a meter that spans the whole range from low to high, but it is much more expensive than the TDS meters or the Pinpoint meters.

 

[ctreefer]

That's perfect then, I've been planning on getting a refractometer for the longest time, now I can kill two birds with one stone with the pinpoint salinity meter.

thanks Randy.

 

[Randy Holmes-Farley]

You're welcome

Happy Reefing.