It is not difficult to lower the dKH (stands for German degrees of Hardness) and the pH of your water, should it be too high. You can do so in several ways, but the one that is safest and probably the easiest one to implement is the use of seltzer (also called carbonated or sparkling) water. This will lower the pH because it contains carbon dioxide. Carbon dioxide mixed with water forms carbonic acid, and that acid reacts with the buffer, and lowers it in the process. In doing so, the dKH goes down and, when that happens, the pH will go down as well.Mind you, even though the principle is simple and actually making it work for you is easy, it will take time (mostly depending on how high the dKH is and what its make-up is) to fix.

The buffer contains many carbonates, bicarbonates and also borates. Depending on which one is more prevalent it will take fewer or more additions of seltzer water (or similar) for this process to work for you.

Note that when you use this method you will need to have both a dKH and a pH test at hand, as you will need to test frequently to determine what is happening to both, so you know when you need to stop and whether or not you are adding too much seltzer water at a time (if you do the pH will fluctuate too much and this creates stress).

Since I have no control over how you use this method I cannot take responsibility but if you follow the directions the method is totally safe for ever type of tank. Swings will occur and need to be minimized as much as possible.

Each time you add seltzer water the pH will fall because of all the carbon dioxide that is released. This CO2 is quickly neutralized by the components of the buffer though, and when that happens the pH goes back up.

We need to minimize those swings in the pH as such swings bring about stress. Stress can lead to outbreaks of parasites, something we certainly want to avoid.

Here is the suggested method:

• Measure the pH, write the result down on a special sheet of paper where you can keep track of the changes that occur as you progress with the additions of seltzer water (or similar type water that contains carbon dioxide).

• Measure the dKH, write that result down too, as above.

• For you to use this method we have to assume that the results above are too high. For example the pH is 8.4 or so in the AM (when it should be more like 8.2) or the dKH is over 10 and you need to lower it so the calcium levels go up (high dKH levels prevent Ca ion levels from rising).

• For every 20 gallons of water in your tank add 1 ounce of seltzer water but do not exceed a maximum of 4 ounces at a time.

• Add this seltzer water to the sump. If you have to add it to the tank directly, spread it out over the entire area adding a little bit here and a little bit there, making sure that the seltzer water does not hit a coral when it mixes with the tank's water. Indeed this would put the coral in water with a sudden much lower pH than it was in, creating stress.

• Wait about 60 minutes and test the pH and the dKH and add the results to your sheet. Note whether there are changes. In all likelihood if your pH and/or dKH were real high, there will be none. This is normal. All the carbon dioxide was neutralized by the components of the buffer and did not lower it enough to show a change yet.

• After that one hour (if the pH and/or dKH are still too high) add another dose, using the same method as above.

• Wait 60 minutes and test again. Note the results and write them down. If no change as occurred, add another dose.

• If a change has occurred we need to lower the dosage we are adding.

• In essence we have a dual situation here: the carbon dioxide has started to affect the dKH and pH, or it has not.

Situation 1: No change has occurred

• Continue dosing as above

• Write the results down

• Keep doing so until a change does occur and your testing shows it.

Situation 2: A change has occurred

• As indicated above, if a change has occurred, you need to lower the amount of seltzer or similar water you are adding. This is necessary to avoid too rapid pH changes (remember, too rapid changes create stress).

• If a change has taken place, divide the amount you are adding by two.

• Again, wait 60 minutes and test again, writing the results down.

• As you continue this treatment, the dKH and the pH will continue to go down until you reach a point where it is at the levels you want it to be.

• That is, obviously, when you stop adding seltzer water

It is a good idea to continue to test for a while after you stop as in many cases the pH and or dKH will go back up and a few more treatments may be necessary.

Once your pH and dKH are under control you should watch out for its variations and if any occur you should try to determine why or you will find yourself repeating this treatment over and over.

If the pH in your tank has a tendency to creep up, you may need to test the hardness of the raw water you use. If that is too high, adding salt will make it even higher and can be one of the reasons why the pH of your tank rises too much.

Another factor to consider is the strength of the Kalkwasser you add. If you have a high evaporation rate and you add lots of KW, you may very well find that the pH will start to rise again. Providing your calcium levels stay in the right range, you may wish to consider lowering the strength of your KW by using less calcium hydroxide or diluting what you use before dripping it in the tank.

Sometimes the type of rock you have can lead to a rising pH. Limestone can result in a pH that wants to keep going up as it slowly releases compounds in the water. If that is your case, you may need to remove that rock and replace it by a different kind.

Generally though you will find that the two main reasons for too high a pH are:

• the raw water you use has a high dKH to begin with
• you need to add lots of KW and that makes the pH go up.

If the pH of your raw water is too high, use the same method as described above to lower it before you add salt. This will counteract the rising pH after you add that water to your tank.

If the amount of KW you need to add is the cause, dilute it but do watch your calcium levels. If your calcium levels fall, you can always add diluted KW plus another form of calcium to maintain desired calcium levels (in this respect you may wish to read the article on Pure Calcium in this Library under the section Product Related). A mix of the two will give you an acceptable pH, a correct dKH and enough calcium for your corals.

Again, please follow the instructions above and not dump massive amounts of seltzer in your tank to speed up the process. The rapid pH fluctuations will cause too much stress and can result in losses of corals and in fish breaking out with parasites.

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