adding vinegar to Kalkwasser

[eleyan]

I found this article referenced in some other sites. The author claims that mixing kalk with water in a top off container produces too much precipitated calcium in the container because there isn't enough dissolved CO2 in the small container to fully disolve the Kalk. His solution is to dissolve 1 teaspoon of kalk in 15ml of distilled vinegar first and then dilute the mix in 1 qt of RO water. He swears by this and claims that no harm comes of it. Has anyone tried this method?

http://www.reefscapes.net/articles/breefcase/kalkwasser.html

[Texreefer]

yes it can be done but with caution because it can significantly drop your ph or drop it too fast

[eleyan]

so what are the precautions to take other than dripping slowly? The setup I currently have is a 6G reservoir connected to a float valve in my sump. I basically add 1 teaspoon of kalk per gallon every time I fill up the reservoir (6 teaspoons total), which is every 3 days (that is how much evaporation my 175G has). if I follow his recommendation I have to add 4 teaspoons + 60ml of vinegar per gallon (24 teaspoons + 360ml total in my 6G reservoir) which sounds like a recipe for some pickled fish :) what is a good amount to add per week in a 175G tank with a mix of softies LPS and some SPS ?

[Richard]

If you follow the directions in this article and drip it in just as you would regular kalkwasser you won't have problems with low ph.
http://www.reefscapes.net/articles/breefcase/kalkwasser.html

When you combine kalkwasser with vinegar you are making calcium acetate. The acetate becomes a carbon source for bacteria. So it can be similar to dosing vodka in that you may see a reduction in N & P but you can also end up with too little nutrients for your corals. This is what happened to me when I was using it. I saw a noticable reduction in algae growth which was good but after a while my softies were not at all happy and I had to back off on the vinegar.

[eleyan]

Thanks Richard. That is good for me right now because my tank is going through a red slime plume. if I it reduces P & N then it will help kill the red slime. What is a good guideline for how much kalk to dose per gallon of tank water per week?

[JimD]

Reducing "P & N will certainly help control Cyano, more flow in the affected area will also help... Theres no real 'kalk per gallon' formula, basicly, kalk will reach a saturation point with a Ph of around 12.4, you can add as much or as little and the Ph will never get above that level. It really depends on the size of the container and the ammount of top off needed to compensate for eveporation. Idealy, you want to top off 100% with fully saturated kalk... When you notice a decrease in normal Ph, you know its time to recharge your dispenser.

[eleyan]

Well, I started adding vinegar tonight. I added 4 teaspoons of kalk + 120 ml of vinegar to my 6G top off container. It should drip slowley over the next three days through the top off float valve in the sump as the tank water evaporates. I measured my tank params before I started as a reference:
nitrates 20 (I can't tell whats causing this to rise)
Ca 375
Kh 8-9
PH 8.2-8.4

I will update the thread with more params as time goes.

[matt]

The vinegar increases the solubility of calcium hydroxide; which makes for KW with a higher level of calcium, and in the tank the hydroxide ions combine with carbonic acid to produce (bi)carbonate ions. From what I remember, it's fairly normal to be able to raise the strength of your KW about 15% before you get to the point at which the vinegar will supress your ph too much. Since the vinegar lowers the ph of the KW in your dispensor, it's thought that you can safely add more KW to your tank, although in real world situations this is only an issue when you have very high evaporation rates, like more than 5% of tank volume daily. For most of us, the limiting factor in how much KW we can dose (slowly) is our evaporation.

This was a pretty popular topic several years back when many people were trying to use KW to completely replenish Ca and Alk for a reef tank, as in the old berlin method days. Now most reefkeepers use KW as a partial supplement and to keep ph levels high, combining it with either a calcium reactor or 2 part Ca and Alk spplements.