re:Aquatic Plants Digest V1 #72

>From: KB Koh <KB_Koh at ccm_ipn.intel.com>
>Date: Tue, 16 May 95 08:34:00 PDT
>Subject: PH

>All species doing well except for Limnophilla and Acorus. Acorus is 
>worst because it did not even grow new roots.

Most of the Acorus you buy from the stores are grown emersed, and are
very difficult to grow sumberged.  I'm not surprised you are having

>I discovered my PH is way too low, going below 5.0 even with 25% water 
>change weekly. Quickly did a 50% water change and PH went up to 6.5. 
>My question is what can cause the PH keep going down? I have a large 
>drift wood. Could this pose a problem?

The driftwood could be the problem.  Also, you could have soft water,
with very little buffering capacity.  Ideally, the carbonate hardness
should be 4dKH or higher.  Ordinary baking soda (not baking powder)
can be used to boost KH.  For a 50 gallon tank, try adding 1/2 level
teaspoon at a time till you gradually get to the desired hardness.

>Tank size is 50gal. with 2 Black Mollies, 4 Zebra Danios, 1 Flying Fox, 
>1 Pleco. Filtered by Fluval 303 with ceramic rings, active carbon and 
>fluval sponge. 1 Triton, 1 Aquari-Lux and 1 Phillip Super Daylight 
>bulbs. Coarse sand gravel and many stones.

The carbon could be removing nutrients that your plants could use.