How can I increase the carbonate hardness?

[fishorama]

Lois, you want at least 50ppm (or 3 GDH, German degrees of hardness, it will depend on how your test kits reads it) of both KH & GH. My tap water is just about that so I rely on water changes mostly . But at my old house it was lower & I added crushed coral to the filter. I never had it completely dissolve over several years. I used ~2 TBSPs in a 20g tank. Check your GH too, usually, but not always low KH =low GH. & your water may change over seasons too, depending on where your water comes from, it changed where I used to live. Let your tap water sit out in a glass or bowl before testing pH. Many water co. raise it temporarily to avoid wear on supply lines.

I too, bought a giant bag of crushed coral & have enough for me & everyone I know, lol, TTA. I should test (everything) more often especially since I have a lot of plants these days. There are always things we can do better...I still need to read several articles you've posted.

 

[TwoTankAmin]

To raise both GH and KH simultaneously, add calcium carbonate (CaCO3). 1/2 teaspoon per 100 liters of water will increase both the KH and GH by about 1-2 dH. Alternatively, add some sea shells, coral, limestone, marble chips, etc. to your filter.

To raise the KH without raising the GH, add sodium bicarbonate (NaHCO3), commonly known as baking soda. 1/2 teaspoon per 100 Liters raises the KH by about 1 dH. Sodium bicarbonate drives the pH towards an equilibrium value of 8.2.

Since you have a 60L tank, you would add .30 teaspoon for each dH you want to raise it. You may end up with a pH in the 8.2 range. The problem with using this is a build up of sodium can be fatal to many fw fish. I would strongly suggest you go with the coral if possible. It is simple and has a wider margin of error than baking soda.

Calcium chloride is a PITA to dissolve unless there is acid involved. I used to start with 20 gal. (76L) of tap water at pH 7.0+ which was run through a few cups of crushed coral in a H.O.T. Magnum for 24 hours. The coral raised the GH/TDS between 15 and 20 ppm. I then added a couple+ teaspoons of Epsom and it raised the TDS by about another 75-80 ppm. Finally, added about 1/4 teaspoon of sodium bicarb to goose a few more ppm of TDS without raising the pH.