How much will driftwood drop my pH?

[Bottomfeeder]

I have a 30g tank, and my ultimate plan for the tank is to have a Ctenopoma, a Flying Fox, a Clown Pleco and a Nandus. I have all but the Nandus While the other fish are quite adaptable to different pH I have heard that Nandus nandus hate low pH. That clashes with the awesome pile of driftwood in the tank. I have 3 relatively large pieces. Will that drop my pH too much? I suppose the lowest I would want it is 7.0, and I'm not sure what it's at now. If it will lower my pH too much I will go buy a bag of crushed coral, although I'd rather not because the lfs only has 15lb bags, and I'd just be adding a few pieces. What do you guys think?

 

[yayfish24]

Instead of buying crushed coral get a test kit. If you need to add something like crushed coral to raise your ph check with people in your area who might have a salt water tank and see if they would sell you a little bit of gravel. They might even have some left over too.

 

[Bottomfeeder]

Eh, it would be easier to get crushed coral from the lfs than to look around for that. I do have a test kit. Water is being tested as we speak

Edit: It's under 7
About 6.8
Crushed coral it is.