Originally Posted by SinCrisis
boo, my tank is 8.0 and my drifwood isnt working as well anymore...
That is fairly high and I suspect there is a corresponding hardness. Wood is not in my experience a reliable water softener/acidifier, and I recall a post from another member a week or so ago about pH dropping .2 with wood, so that's not much. Don't know what fish you have/want, whether considering peat or RO would be practical...
If you could get your pH down to the low 7's you would probably be OK plant-wise. Yesterday I was doing some research to see what info I could find on potassium excess to aid Aunt Kymmie with her Echinodorus problem (another thread) and happened to read in one of Peter Hiscock's books about most plants being acidic water in origin (I knew that part) and that the major factor that affects the quantity of nutrients in water is hardness which in tap water should not be confused with pH and acidity/alkalinity. He maintains that some nutrients especially micronutrients are less available in hard water, so soft water plants don't generally thrive, but adding CO2 to moderately hard water usually will allow softwater plants to be maintained [this is a highly condensed version of the entire argument]. We all know that CO2 addition lowers pH, so I am myself certain that all this is connected.
I have had Vallisneria grow profusely in alkaline tanks with livebearers (dolomite in the filter or substrate raised the hardness and pH to mid-7's) but it rots to pieces in short order in acidic water.
Ceratopteris is probably delicate enough that it would not adapt to a great deviation, but if you can find some it may be worth trying.