Thiel Laterite, Shop Lights and Diffusion Bells

Subject: Thiel laterite (again)
> I've been helping a guy at work design a nice plant tank.  He's 
> gathering materials for a while.  Today he brought in a jar of T
> Aquatech laterite for me to see how it looked compared to Dupla.
> never seen TAT laterite before but have used Dupla's.
> When I opend the jar I was expecting a dark red clay powder but 
> a brown colored sand-sized material instead.  The main thing I
> noticed, though, was the strong humus smell.  It sure didn't loo
> smell like any laterite I've seen before; it seemed to be more s
> soaked in peatmoss extract.  My co-worker is concerned it's not 
> laterite and possibly not effective.
> I rummaged through the archives of this list with Thiel as the s
> word and have found a few people who have used it (and Dupla) an
> reported good results with both.  But I guess my questions are:
> 1) Is the TAT stuff really laterite (leached Fe/Mn/Al clay)?

He says it is.
> 2) Does it matter so long as you get good results?

Not to me.  I have used it in a number of tanks, and so have a 
number of my friends.  Everyone has been happy with it, and there 
have been no problems reported.  I have seen all the tanks, and 
they are beautiful, lush, long term tanks.
> 3) Do the results last as long as Dupla?

Who knows?  I've never had a problem with either "wearing out"<g>

Subject: Shop Lights

> I have a 55G currently stocked with mainly small Sth Am. fish wi
> a few, non-thriving plants.  I wish to concentrate more on the p
> and require some advice as to how I am best to procede.
> Firstly I want to add another 2 tubes to the one I have.  From w
> I've read many people use standard shop lights, so I'll investig
> these.  Are there potential problems with these? eg water resist
> etc, and also they don't seem to have much in the way of reflect

I use a lot of shop lights.  I have found that the cheapest ones 
(the $10 or less variety) do wear out bulbs much too fast.  You 
can get better ones for about $30 though, that have a better 
reflector, are a little more "finished" looking and less flimsy.  
These seem to be equivalent to aquarium strip lights, hold two 
bulbs, and are _much_ less expensive.  That said, these days, I 
replace _all_ ballasts with electronic ballasts and use T-8 SPX50 

Water resistance is not an issue if you use them over a glass 
canopy.  If you don't, you'll probably need waterproof end caps no 
matter what kind of fixture you buy.

The shiny white interior of a shop light is actually a pretty good 
reflector.  It's better than the white plastic inside many 
aquarium "reflectors".


Subject: CO2 Bell

> Will someone please explain how a home made CO2 bell works?

A diffusion bell works by keeping the CO2 in contact with the 
water.  Since CO2 dissolves quite readily in water, this MAY be 
sufficient particularly in a moderately lit tank.  It is 
definitely better than just letting the CO2 bubble out at the 
surface, but not _any where near_ as efficient as either a CO2 
reactor or even bubbling the CO2 into a filter.

Besides the slow diffusion rate, the other problems with this 
system are that unless your rate of diffusion matches or exceeds 
your production (or introduction) of CO2,  the CO2 will fill the 
bell, then "burp" to the surface and be wasted.  Also, there are 
other gases that will get trapped in the bell, leaving less space 
for CO2.  eventually, you will get to a point where you have to 
dump what's in the bell and start over again, and it's really 
guess work as to when this needs to be done.

> Reading postings in the archives leads me to believe a solid
> plastic container is used.  So I can use a small water bottle w
> one end cut off.  But how does water continually cycle into the
> to mix with the CO2 without letting the CO2 escape?  If the bub
> keep going into the solid bell, it will eventually fill up.  Wi
> still continue at that point?

When I played around with passive diffusers for a while, I made 
several by using an inverted babyfood jar.  You are right that on 
it's own a diffusion bell would flip once it had enough gas in it. 
 The way this is solved is to attach it to the wall of the tank 
with suction cups.  I just glued on the kind that hold airline 
tubing or heaters in place.  Actually, if you really want to do it 
this way, and there are much better ways, Tetra sells very nice, 
easy to use, unobtrusive diffusion bells, and at 2 for about $10, 
to my mind they're inexpensive enough that I'd rather not waste 
time making them myself.

Karen Randall
Aquatic Gardeners Assoc.
Boston, MA