Q about marble in ponds

[satyra]

So ive been doing some research on marble stones in the ponds. Ive read that it can raise Ph, but i cant find any info on whether it will continue to raise the ph in the pond forever, or if that effect eventually wears off. I found some real pretty marble stones that i would like to put a little bit in the pond. The amount i wanna use is small, and the pond is about 400 gal right now but its not filled up to the top, total it can hold about 600gal. Im waiting to fill it up more until we get a screen or net or something over the top to keep the fish in and stray cats, or whatever else might wanna mess with the pond, out. Right now the ph in the pond is 7.2. Just set it up recently so the ammonia is around .5 - 1.

So ive had a few different options in mind -

1 - try putting just a little tiny bit of marble stones in there at a time so hopefully the ph doesnt rise too high too quickly (best case scenario theres enough water to keep that from happening), and hope the effect wears off eventually.

2 - try to soak all the marble stones for a while and see if they stop raising the ph, then put them in the pond

3 - or if its hopeless just return them and get something else...the marble stones were the prettiest though :( my other option was some semi-smooth light grey-ish river pebble type rocks.

So have any of yall tried the marble stones in your ponds? If anyone needs to know exactly what they are, we got them at the local home depot, they had pallates full of them. On another note, i have put big chunks of limestone rocks in my tanks before, brand new, and they have never raised the ph of my water, like they are supposedly supposed to do, so not sure if these marble stones will do the same thing or not. Thanks for any info!

[NDSE]

Marble is metamorphic limestone (usually dolomite CaMg(CO3)2 or calcite CaCO3), and unless you have very acidic (< 6.0 so) water to begin with you are going to have very little dissolution. If your water is already slightly basic ( > 7.5) you will get some of the marble into solution, but it will be very little and unlikely to change your pH more than a tenth or so (you will get more fluctuation from fluctuations in CO2 concentrations). I say unlikely because it depends also on the carbonate hardness of your water as well, but for the most part in N. Tx water you are going to see very little change in the water chemistry by adding limestone rocks.

[cichlidtim]

blue granite is good too