[niko]

Pseuro,

I don't know if you know this but you must check the rocks you got for presence of Calcium.

If you don't know how please ask here and you will get an answer.

I personally don't think you have to boil the rocks. Scrubbing them with a brush under running water should be enough.

--Nikolay

 

[niko]

Pseuro,

I said that I personally don't think you have to boil the rocks but other people may disagree. Please wait a few days if you can and see if anyone posts a good reason to boil the rocks.

Testing for Calcium is needed because you will be using the rocks in a tank that is injected with CO2. The CO2 will make the water acidic (pH will go below 7.0) and that will lead to Calcium disolving in the water. The result will be:
- an increase of the water hardness - KH (and maybe GH too).
- pH never decreasing despite pumping more and more CO2
- thick white surface foam

To test the rocks for Calcium you need to get a little strong acid - any kind really. Put a few drops on the rocks and see if the rock "fizzes", meaning tiny bubbles forming like foam or like soda water. You can use acid that you get from a pool store (muriatic acid, used to lower pH in swimming pools), or a household all-purpose cleaner that has phosphoric acid listed as one of the ingredients.

Something else before testing the rocks is to make sure is that your gravel doesn't have Calcium If it "fizzes" you must replace it.

--Nikolay