I got a nice haul of lave rocks and wondered if these buffer the PH? Can't wait to put'em to good use. )

I did a quick google search and didn't see anything on lava rocks. But from what I did read most aquarium rocks raise ph while most woods lower it. Sorry I couldn't help more.

Not that i'm aware of.. I ran lava rock as media in my filters for years and it never did anything to my Ph.. I had lots of Ph problems and i went to petco and grabbed a 20lb bag of crushed coral and dropped it in my sump and since then my ph has been dead at 7.4 for the last year..

crushed coral, IMO is the best to buffer Wa water supply.

Lava rock won't affect Ph, but be careful, it is pretty rough on fish if they bang into it.

Unfortunately, after a few months of colonization, lava rocks are no more useful than large boulders for surface area. While their surface area is initially greater than that of a smooth stone, it does not take long for enough mulm to fill in the pores leaving a practically flat surface. I would recommend medium-to-small pea gravel as a viable and comparable alternative. You'll still be in the same price range but with more surface area exposed in six month's time.

For the record, I have used lava rock with good success in lightly stocked tanks with really good mechanical barriers before the water reached it. The pores will stay open longer if most physical debris is prevented from reaching the lava rock. I use nylon paint strainer bags from the paint store as a sort of filter sock/filter membrane in most of my tanks and it holds up for mechanical duty for at least a year (with weekly rinsing) before getting too clogged/fuzzed over.

No, lava rock shouldn't affect pH. Most of us around here nave figured out the need to buffer, though, as our tap water crashes from 7.3-ish to about 6.4-ish overnight. Whether you use crushed coral (the easiest go-to solution) or sodium bicarbonate (good 'ol baking soda, add to new water) seems to make no difference to the fish. The goal is avoiding the pH spike that would happen as the tap water degases.

I use small lava rock in my magnum 350 canister filters for years without clogging up since it has prefilter socks over the bins. Very effective filtering and bacteria growth without affecting PH. I mix crushed coral in with the lava rock to keep the tank water at or very close to 7.0 between water changes. Make sure you boil the lava rock first before adding to tank or take the risk of adding something you don't want including (of all things) pesticides. My lava rock bag came with a warning label that states it is not to be used around small children without boiling or heating to 550 degres in an oven. Since I can't cook anything without burning it I chose to boil the rock on my outdoor grill.

I don't like to use it in my tanks for decorations since it can be a hazard to fish and I just don't like the look of it. In my QT I have java moss growning on a nice chunk of lava rock but its so covered that you can't even see the red rock. One thing for sure, Lava rock makes a great growing meadium for free rooting plants (java moss,java fern, anudias, monosolenium tenerum).

No.
Things that will; sea shells, coral, lime stone.

A good way to test if a rock is alkaline (PH raising) is to pour some white vinegar on it and if it bubbles and fizzes some it will raise your PH.
If it doesn't do any thing it is inert and will not affect your PH in any way.

Thanks all. I just wanted to make darn sure It wasn't gonna get to high on me. The rock are for decoration in this case not filtration.

Interesting... I'm setting up a new tank and my pH is running around 7.2. Since I haven't added any Cichlids yet I only have a few feeders in there just to condition the tank. I Added some broken up oyster shells to the filter that had boiled for an hour. That was Yesterday, I haven't checked it since. Someone mentioned that they had built shelters out of oyster shells and it raised the pH. I hope it works.

I was hoping to get some Birchardi. But I just finished reading a post that they breed like rabbits. They are beautiful fish, but I don't think I want to get into that again.. My house looked like a drug lab.