Cheap rock options to raise ph

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Original poster
Jul 28, 2019
I am finding myself needing to raise the ph and kh of my aquarium. Everything I’ve been reading says rocks like limestone will do this. However, for whichever reason I’m struggling to find anywhere that sells them. Is there any other rocks that will and suggestions on where to get them. Everywhere around me just either has huge limestone bricks or rocks that are much too large and expensive or just had a powdered form. I’m just looking for a plain rock that’s not super big so I don’t want to spend 60$ on a big rock that would take up a huge portion of the aquarium and raise the ph too much.
Apr 2, 2002
New York
Crushed coral will work. You can use it as substrate or as part of substrate. you can also put it in a bag in your filter. However, altering one's water chemistry is not a simple process. There are many considerations. Here is some good basic information on this subject. You can go step by step or just click the final of the three links below

Go to
Click on Your First Aquarium
You want to read two sections, both are found by clicking on Practical Freshwater Chemistry

This will give you an idea of what is involved in altering your water parameters. There are two issues to consider when doing this. The firat is to learn what it takes to target a change and then how to keep it that way. The second is how you will do water changes so as not to change the parameters. I can tell you from experience it is harder to effect smaller changes to parameters and it is harder to lower pH and hardness than to raise these things.

Finally, not everything on that site I suggested is complete. For example, the use of Sodium bicarbinate is not for all fish. The sodium component may be OK for rift lake cichlids or sw fish but it is not so good for most fw fish. I would suggest if you choose a method that you post about it in this thread and get feedback before you actually proceed with it.