Adding Kalk

[jackets22]

I need to start adding calcium to the tank. I have some soft corals and I just added a Birdsnest and a Monti Cap frag. My calcium is at 400 would like it bump it a bit.

Adding kalk seems like the logical thing to use. Right now I add essential elements to my top off water. The top off container is about 4 gallons and I plan on adding kalk water after I mix it to the top off water. I dont want any settling in the top off container that is why I will mix it in a different container. My question is how much calcium water after it has been mixed and drained should I add to the top off container?

Thanks

[bertoni]

The limewater can't be mixed with the trace elements supplement for various reasons. Kalk adds both calcium and alkalinity, not just calcium, and it's not useful for raising calcium very rapidly, if at all, because the pH is very high and the solution is very dilute. This article might help:

http://www.reefkeeping.com/issues/2005-01/rhf/index.php

[jackets22]

I realize that the essential elements will not replace kalk. What I am trying to figure out is that if adding a gallon of kalk water to the 4 gal. auto top off water will work or if I need to make all the auto top off water kalk water. I realize that putting 3 parts RO to 1 part Kalk water is going to dilute it. I am not looking to raise it fast or even that much at this point as I dont want the ph to go crazy. I am at 400 cal now I would like to raise it a bit of course for the birdsnest frag and the monti cap frag (tiny). I imagine that they wont be using too much calcium at this point but I want to get used to using kalk and get the calcium up so I can add more calcium dependent corals.

[ksouers]

To know if the kalk can keep up with your calcium demand will take time and lots of testing. Test every week before and after a water change. Record your readings. Note the difference between the after reading from last week and the before reading if this week. That will be your demand. Do that for about a month. Then run kalk the way you described and do the same thing, record before and after. See if it keeps up with your demand. If not, mix a little stronger and do it all over again.

Test the calcium level of your change water. Use a calcium supplement to set it to your desired level. This will give you a standard for your tank to meet.

Start by setting your target level in the tank with a supplement then don't touch it for the month you are testing. The only calcium supplement you should be adding will be to the fresh change water, only enough to set the change water to your target. You will also want to note the levels at the beginning and end of the month. This will tell you if water changes alone can keep up with your demand. If so, you probably don't need kalk. Maybe just a dash of supplement once or twice a month is all you need. If you notice your alk is dropping you most likely will want to use kalk in your top-off even if your calcium demand is being met with water changes.

So, you will be testing your tank for Calcium and alk both before and after a water change. Plus your change water for calcium to make sure it's on target. It would also be a good idea to test your magnesium to make sure it's up to snuff. Well, I did say there was lots of testing involved...
The good part is after you have all this data, and you know what your tank needs, you don't have to test as much :)

Only diligent testing and record keeping can tell you what your tank needs.

Best of luck.

[Agu]

It's pretty difficult to overdose kalk if you're using it as topoff water even at 100% saturation. I wouldn't bother with a 25% saturation to start with.

Other than that ksouers gives good advice on how to determine calcium demand.

[jackets22]

Thanks for the replies. That helps a ton. I will be out buying a alk and mag test kit before I start anything else. One quick question. What causes the alk to go low? Thanks

[ksouers]

It gets used up, just like calcium. Alk is basically just the hardness of the water, so it's just the minerals in the water.

There is an ionic balance between alk and calcium. It can get out of whack and cause calcium to precipitate out of the water. Kalk is naturally in balance and will help maintain the balance without additional work on your part.

Magnesium helps to keep your calcium up, as well. If you are having trouble keeping your calcium up, it's probably because of low mag.

Check out the link that bertoni posted to Reef Keeping Magazine. The article is by Randy Holmes-Farley. He knows this stuff inside out. At the top there is a menu bar, look for past articles. You can search by author. Check out all by RHF to get a better understanding of how it all works. I've had to read them several times before I got a handle on how it works. Some stuff is still way over my head, but I understand a little more each time I read them.

[bertoni]

Corals and coralline algae consume calcium and carbonate alkalinity to produce calcium carbonate skeletons and such. So they drop in a fixed ratio for that reason. There's a few processes that consume only alkalinity, but the volume is usually very low.