# Clay substrate PH?



## Psittac (Jan 29, 2009)

I just replaced my substrate with a cheap DIY/save money clay that I found out about on another forum and after talking to my friend about it I tested the PH.

Unfortunately my PH is at least 6.0 if not lower (my test kit only goes to 6.0 so it could be off the charts)

My question is this, do the expensive clay substrates lower the PH allready? I don't know if this is normal or because I decided to cut corners.

My PH was only at 7.0 to begin with (7.6 tap with neutral regulator) so dropping to 6.0 isn't that scary, it's that it could be off the charts that I'm worried about.

I'm slowly adding neutral regulator now to raise the PH to 7.0 but I need input so I can decide what to do now.


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## Zapins (Jul 28, 2004)

I wouldn't worry about the pH being lowered. pH changes aren't really very important in the planted aquarium contrary to popular belief. I wouldn't add pH changing chemicals though because they frequently can cause problems with overdosing. Clay will tend to be lower in pH in general because it is negatively charged. 

The small grains that make up the clay gather up electrons from other substances like a static charge causing them to be negatively charged. What this does is the clay will attract positively charged molecules like calcium, magnesium, iron, potassium, and hydrogen atoms from CO2 (after it reacts with water to become carboxylic acid) becoming acidic. 

One problem with this occurrence is that the clay will tend to lock up a lot of nutrients in the substrate rather than letting them float around the water column for the plants to use. If you really want to do something (though it probably isn't necessary) you can help release nutrients from the clay by adding some calcium carbonate (CaCO3) to the water, or add a limestone rock, crushed coral or other calcium containing substance to the filter or water. The calcium will bind to the clay and cause it to clump together, releasing the other nutrients that it attracted, the clumping will also improve aeration. 

Overall, you will find that aquariums are very forgiving and extremely precise conditions aren't needed. Just as long as there are enough nutrients, and light to go around plants will grow fine. Don't stress too much!


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## Psittac (Jan 29, 2009)

Wow thanks for that reply.

I'll look into putting some coral chips into my canister filter then.

Where do I get calcium carbonate? I added baking soda tonight, the first dose didn't bring it past 1 kh, the second dose of almost the same shot it up to 7.5 kh

I'm trying to get the hang of balancing this tank now, in the past it was simple, all I had to do was water changes and nothing even really needed to be tested.


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## TAB (Feb 7, 2009)

Your local feed store. Buy oster shells. I used them for a decade as media for a my calcuim reactor on a 240 reef.


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