so how long does it take for crushed coral to work?

[jagsandpits]

i just put about a cup and a half to 2 cups of rinsed crushed coral in a media bad and placed it into the filter of my 20 gallon tank, i want the gh to be like 10-20, its at 5 right now. how long until this stuff starts to work, ill test everyday to see how its going but if it doesnt shoot up atleast by 5 in a week should i add? or is it a really slow process. also how do water changes work, would a 25 % water change mess up the hardness or is it permanent?

 

[coyotethug]

What is your tap hardness? If you are putting soft water in then you probably wont see a huge change depending on how often unless you replace all of your gravel with crushed coral. Even then crushed coral is better at maintaining hardness than elevating it.

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[jagsandpits]

my hardness comes out the tap at 3, the crushed coral put it up to like 4 or 5 in a couple hours

 

[jrthor_85]

If your pH is high, the coral will dissolve slower than if you had lower (more acidic) pH to start with. If your pH is not much concern you can use a little Sulfuric Acid (common pH-down chem) and the crushed coral will dissolve to buffer it. Another less harmful option is to add a little baking soda to the water during your water changes. With tests you'll find out how much you need to use, so just start low and work your way to the proper concentration.