Originally Posted by BeakerBob
Here are some issues of adding to the top=off water:
1) Kalk is very hard on the ATO pump as it will deposit calcium carbonate on the spindle & prop.
2) The tip of the ATO tube that is feeding the sump or tank will plug up fast with calcium carbonate deposits.
3) If you have a one-way valve on the ATO to prevent backflow, it will eventually get stuck open with calcium carbonate deposits
4) Calcium and Alk will be added in equal amounts....any tank imbalance of either Ca or Alk will NOT be corrected.
5) MOST IMPORTANT, should your ATO somehow get stuck on, you will flood the tank with RO/DI and Kalk.
Otherwise, you can do it and it works!
Originally Posted by MizTanks
I think I'll stick with 2part-lol-less room for me to mess up
Jamie - Don't give up on Kalk so quickly. All of Bobs points are valid, but can also be easily addressed - some concerns apply to 2-part dosing as well.
Overall, I prefer Kalk to 2-part assuming you have lower Alk and Ca demands that can be met with Kalk. I've used a Tunze Osmolator for Kalk laden ATO for the past 2 years and the original pump is still going strong ($25 to replace if needed.) The key is to pump only the clear liquid, rather than a slurry containing Kalk powder.
Cleaning the tip of the Kalk line is as simple as giving it a couple squeezes every month or so if you see it becoming clogged.
If the end of your your dosing tube is higher than your reservoir - No check-valve is needed. If it should fail open, no biggie - the pump just runs a few seconds more each cycle.
Kalk is balanced dosing - equal amounts of Alk and Ca - just the way your corals uptake. You use your 2-part to get your Alk and Ca settings to the desired levels, then the Kalk maintains them. The same principle applies when using a Calcium reactor.
As for an ATO sticking "On" - That's bad news whether adding Kalk or not. I assume you have a back up plan to detect and prevent that from occurring.
Here are the pros / cons on Kalk from my perspective,
- It's a "balanced" solution, meaning it adds Ca and Alk in the same proportion as as corals uptake (only one thing to dose.)
- It can be kept indefinitely in a still, tightly covered bucket. Just make sure there is some extra, undissolved Kalk in the bottom of the bucket. After time, you may notice a hard "skin" (Calcium Carbonate) form on the top of the Kalk solution. This occurs when the Kalk solution is exposed to CO2 and creates a barrier that limits further degradation. For these reasons and the high pH, it's best to use a pump rather than constantly opening and closing the bucket to dose manually.
- Some also believe Kalk also has the benefit of being able to precipitate out Phosphates.
- The drawbacks are similar to 2-part (at least the Alk component) in that Kalk when fully saturated has a pH above 12 and must be dosed/dripped slowly.
- When used in ATO, your Ca and Alk dosing is tied to your evaporation rate. Depending on how many stony corals you have in your tank, this might be more or less dosing than is needed and can result in too high (or low) Ca and Alk levels.
- Kalk doesn't provide as much Alk and Ca as can 2-part. High demand tanks will reach a point that Kalk dosing alone cannot keep up with the Ca/Alk demands. At that point the addition of 2-part or a Calcium Reactor is needed.
You also have the option of adding Kalk using a dosing pump (as opposed to using kalk-saturated ATO.) This give you the ability to control ALK/Ca dosing independent of your evaporation rate and you can dose overnight to counter your tanks diurnal pH swings.