pH of my tank will not go down.

Question
Hi,
I've spent the past few weeks setting up a new brackish tank for a figure 8 puffer. I have it completely set up and its been cycling for a few weeks. I tested my water today and everything seemed normal, all except for the pH. The pH in my tank was right around 8.2, which is a bit too high. I thought it would be a simple fix since the tank has no fish and I had some pH Down. After adding the pH down a few times the water was still right at 8.2. I tested my tap water and it was 7.4 and I even experimented by adding the salt I used in my tank to some tap water and it still came out as 7.4 so I was able to rule that out. I have sand which is supposed to be neutral pH and not supposed to change it and plastic plants as well as some assorted rocks and a piece of driftwood that I bought from my local fish shop. At first I thought it was the driftwood but i read that driftwood naturally lowers the pH. What could be causing this? Is there any way I can fix it?
Thank you,
-Nick

Answer
Nick,     I have been in this business a long time and this is something that I don't see often and I have no explanation for it. I don't know if there is anything about it online. I shocked one of my professors over this once. First if you have well water it could be a mineral problem but, I doubt it. This is going to sound stupid and your going to shake up your bacteria but it will settle. Change your stone !!!!  I don't know why but sometimes there is something wrong with the stone and if I ever run across it again I will test it but, I don't really work with the one on one except here now. Also just some info on brackish tanks since you have to change your stone (sorry) make sure your stone is the medium size and go with natural colors. Also try to keep your plants and decorations natural. They like that it takes away stress for you and them. You have to get that pH down for sure. It is pure saltwater tank levels. Just some Great fish suggestions for your tank they may be abit hard to find but, I am sure they could be ordered. Scat's are just beautiful green with dark green spots then as they get older they become almost a greenish silver with black spots ( I had a red bellied same but a red belly) mono sabae's they are the angel fish of brackish silver with black stripes, bumble bee gobie's, little flounder. They will all go well with your puffer just remember as your puffer gets larger they get abit more aggressive so add his take mates one at a time as soon as your tank settles back down. I just want to add that you can not put sea shells or corals in these tanks just like fresh water or it buffers your water and will keep it at saltwater pH levels. So if you have them in there take them out do a partial water change and you won't have to change your stone. Good Luck, Tina