Hot Gravel & Laterite source (fwd)

---------- Forwarded message ----------
Date: Tue, 15 Aug 1995 13:08:38 -0400 (EDT)
From: Earle Hamilton <ehami at sunny_ncmc.cc.mi.us>
To: Majordomo at ActWin_com
Cc: psmel at sunny_ncmc.cc.mi.us
Subject: Hot Gravel & Laterite source

Tried responding directly to Nick Livingston re substrate heating but 
message didn't take so I will try through the general mailing.  Sorry if 
this is boring to others of you.
Nick, Phil Smelt and I wrote the hot gravel article telling how to build 
a pvc heater cheap and good.  Yes, it really does work.  I would suggest 
you keep the heater size to about 1 watt per gallon and set another 
heater/thermostat in the tank at a lower lever for the cooler wx 
requirements.  While the ugh works, there is still some question in my 
mind as to how necessary it is.  I am doing an experiment where 1/2 of a 
230 gallon tank has ugh with laterite and the other half has ugfilters.  
So far there is no strong indication of difference between the halves of 
the tank with both sides doing great.  I think this is because I found an 
almost free source of laterite.  If you read TOA you will note they 
recommend using 1/3 laterite mixed into the gravel and use that mix for 
the bottom 1/3 of the tank.  This is in conflict with the Duplairit 
instructions which would have you use much less.  Since Duplairit costs 
about $50 per pound and since I had free laterite, I used about 35 pounds 
of laterite for the 1/2 side of the 230 gal tank.  I suspect the 
translation from Ger to Eng in TOA was a bit muffed because with that 
much laterite in the tank some dispersed across the plexiglass barrier 
and into the ugf side.  Thus there was considereable suspended laterite 
throughout the tank.  It took several weeks to clear but eventually the 
tank was fine.  So I don't know if my approximately equal growth on both 
side is becuase of lots of laterite or in spite of lots.

Source for laterite --- When I discovered this source I saw it as an 
opportunity to make a buck but since I have a wonderful young wife who works 
and makes big bucks (I don't need the money) and since I'm retired, I 
decided not to go commercial.  Laterite is available in 50 pound bags for 
about $10.  It is used by potters to make clay pots.  It is similar to 
terra cotta but not the same.  Most potters don't even know they are 
working with laterite but I happened to stumble on one who knew fish  and 
pottery who gave me a 5 gallon bucket of the stuff.  It looks exactly 
like the Dupla stuff.  Skeptics will challenge the chemical composition 
difference but I won't accept the challenge - Im lazy.  Not so different 
than using sand blasing grit at cent per pound vs mail order packaged 
stuff and many times the cost. 

Nick, if you have any questions re building or operating your pvc heater, 
give me a mail call.  Also, I wonder if any others out there are building 
the pvc system described in AFM July issue.

One more unrelated thing-if any of you reading this list are serious 
about plants and are not getting the Aquatic Gardener- then shame on 
you. I just got my first issue and recommend to all.  Subscribe by 
sending $15 to Dorothy Reimer
               83 Cathcart St
               London, Ontario
               CANADA N6C 3L9
Thank you Joanne for steering me to TAG.  Nuff for now - Earle