Re: phosphate substrate & bubbles from new water

> > While there are several sources for lateriate, I would suggest K
> > Schoeler Enterprises Inc., 241 County Road 42, Apple Valley , MN
> > Telephone 612-432-9608.
> Just as long as you know that this is not "straight" laterite.  
> According to the information Karl released on the Newsgroup, it 
> also contains phosphate and nitrate.

Yes and that may be a very good thing. About the only safe place
to have higher concentrations of phosphate is in the substrate.
While it is possible to add macro nutrients such as nitrates
and potassium in solution, this is not a good idea for phosphates
since this will result in green water. The guys doing the botany
experiments often use lake sediment covered with a 1" layer of silica
sand to prevent leaching. Others use a mixture of manure and soil
with a similar top layer. All of those substrates contain considerably
more N-P-K and other micro-nutrients than laterite in addition to
humic material. Experiments seem to show than about 5% humic
material is optimal but since the concentration of N-P-K is highly
correlated to organic content, a total organic content of 20% is
nearly optimal. Note that manure or composted manure does not
contain a large humic component but it is a very effective substrate
additive. One must take care not to disturb the substrate and in
some private e-mail discussions, we seem to feel that the chance
of a green water algal bloom is much higher. However this is very
easy to deal with by maintaining sufficient N-K in solution to
encourage uptake by fast growing plants or by using a diatom
filter. The diatom filter has the advantage of removing the phosphates
and other macro nutrients captured in the bio-mass of the algae which
prevents a re-occurence of the cycle.

> From: rbil at mail_island.net
> Subject: Effects of Water Changes
> got the water tested). Immediately (and I mean within minutes) 
> following a water change, photosynthasis (sp?) is like super 
> charged. Bubbles pour out from plants throughout the aquarium!

Sorry to disappoint you, but those bubbles are simply dissolved
gases coming out of solution from the cold tap water as it warms
up. Some treatment plants add CO2 to decrease hardness (I've read)
but more probably those bubbles are primarily atmospheric Nitrogen
and Oxygen.