Guys, I'm not trying to start anything, but "PH shock" is an outdated myth. The thing one has to worry about is called Osmoregulation. This means the ability of a fish to balance the water in their bodies to the water around them. Fish can tolerate up to 1.0 PH level difference by something like C02, or something relatively harmless. 1.0 difference is huge! Something like 10 times. The problems develop when the cause of such a huge swing is caused by something like ammonia, then it can become lethal. Have you ever received a shipment of fish delivered overnight, opened the bags, and smelled a strong smell of ammonia? This is bad, and the fish should be placed in clean water immediately. No fumbling around with dripping and such. Why? Because when fish expel waste in a sealed bag, nothing really happens until you open the bag. Once opened to fresh air, harmful ammonia immediately builds. This is why you get the smell when you open the bag. This changes PH of the water in the bag faster than you can say, "man that smells like ammonia". This is why most everyone into expensive fish like Discus these days (well, except for a few) use what is known in the trade as the "drop and plop" method, to prevent this from happening to fish that cost up to $300 each. This is done by floating unopened bags in the tank for around 30 minutes to equalize the temp. Then the bag is opened, the bag is poured through a large net over a bucket, trapping the fish in the net, and allowing bag water to pour into a bucket, and the fish placed in the tank. The fish recover fairly quickly, and it's much safer than allowing expensive fish to risk having their gills burned by ammonia exposure.