>>>My plan is to let a sack of one or the other either float in my power filter, or just let the sack float in a bucket of water to be used in a water change later.<<< I can't speak from experience, but I would think that the oak leaves would have a slower effect than peat on changing water conditions. Peat has more surface area and has physical properties that are more reactive. Several folks on the Killie Talk email list have gone into details on this subject, so you may want to scan their archives as well (www.aka.org and follow links). As a practical matter, try putting a sample of both in separate containers and track the changes in water over time. This will give you a sense of how your leaves (Southern Pin Oaks) reacts to your local water. You could even try putting some in a power filter and testing that as well. But be careful, a tank with a full bioload will act differently than an empty jar or bucket. Also, as you lower the pH, you also reduce buffering capacity so it's easier to crash a tank. (Hey! Chemistry types, did I get that right?) Lastly, I have some more info on the properties of oak leaves that I gleaned from the book I'm reading. I'll try to transcribe that info and pass that on by next week. Nothing dramatic, just more explanation on the chemical make up of oak leaves. Bill Vannerson McHenry, IL http://vannerson.home.att.net/ ------------------------------------------------------------------------- This is the apistogramma mailing list, apisto@listbox.com. For instructions on how to subscribe or unsubscribe or get help, email apisto-request@listbox.com.