Re:Growing conditions for plants and alg


 >> The reason why I initially aimed for 7.3 and only about 15 mg/l of CO/2
was some concern about how long the 1500g CO2 bottle would last. In this big
tank (open)
 it's really bubbling away! The rate in the bubble counter is just about  too
fast to count and the valve is open at least three fourths of the time. <<

 Are you using an efficient means of diffusing CO2 into the tank water?  I
hope the CO2 is not simply bubbling out the top of the tank.  A properly set
up reaction chamber will dissolve all of the CO2 in the water without any
excess escaping at the surface.

 Subject: Clay vs plastic pots


 >> Good idea. But why do people usually suggest 'clay'. <<

 There' a very solid scientific reason for me to use clay pots... This is what
I have around.<g>  I know people who do equally well using the cut off bottoms
of soda bottles.

 Seriously, there _is_ one reason that I prefer clay, and that is that because
of the slightly rough surface, it is pretty easy to get Java Moss attached to
it.  And once that is done, you have a permanently "hidden" pot.

 As far as clay contributing anything in the way of iron to the tank, I kind
of doubt that.  I know that clay changes in some very basic ways when it is
fired, and unless I saw some study that suggested otherwise, I suspect that
the iron is pretty firmly bound up.  A fired clay pot is a long way from it's
original clay or even greenware source.

 OTOH, it may be porous enough to provide sites for denitrifying bacteria,
which might be advantageous.

  E-mail from: Karen Randall, 15-May-1995