re: CO2 Questions

>  From: "Yen, Yimeng" <YYEN at biochem_medsch.ucla.edu>
>  Hi, I have a 10 gallon tank which I am using as my "first" plant tank.  I am 
>  currently using a DIY yeast reactor (1 cup sugar, 2 tsp yeast) to provide 
>  CO2 for my tank.  I realize that the amount of CO2 is probably impossible to 
>  control for this type of reactor.  I read all sorts of posts about how 
>  can get good bubbles with their reactor and I wonder how they do it.  My CO2 
>  only seems to bubble for 4-5 days.  In the beginning, CO2 is coming out of 
>  the reactor manically.  In fact, I lowered the pH 1.5 - 2.0 points within an 
>  hour (something my plants love, evidenced by a TREMENDOUS increase in O2 
>  production), but something that my fish hate me for.  After 3 days, the 
>  bubbling dramatically decreases.  Am I using the wrong kind of yeast?  I'm 
>  using the Fleishmann's yeast.  I thought perhaps it was the fact that the 
>  yeast settle to the bottom of the 2 liter bottle, so I rigged up an 
>  Erylemeyer flask with a rubber stopper which contains a stir bar powered by 
>  mechanical stirring device.  This has made the yeast last about 2 days 
>  longer.   Any comments?

For a 2-liter CO2 generator, I use 2 cups of sugar and 1 tsp of yeast.  The
brand of yeast makes a little difference, but not much other than how quickly
it begins to bubble.  I fill the generators to within 3" of the top and cut the
bottom of the air fitting on my cap to a 45 degree angle to help drip off
yeast/sugar mixture that splatters against the top due to fizzing. 

My tap water has a KH of 5 (85 ppm CO3-).  To keep the pH from crashing in my
CO2 generators, I add 1 tsp of baking soda (sodium hydrogen bicarbonate).
Adding this to my mixture (with my tap water) causes the yeast to start out
slower and to last longer (3 weeks of useful fizzing, with fizzing continuing
for about a month and a half).

>  On another note, a question about shrimp.  I just added some shrimp and 
>  otocinclus to my tank, (previously I only had one black molly for cycling).  
>  I'm wondering about what kind of load the invertebrates put on my tank.  The 
>  shrimp are basically feeder shrimp, which the guy at the store said eat 
>  algae.  I got 7 for a dollar and tossed them in.  The guy said that they get 
>  no bigger than 2 cm, but I am wondering if I put too many in my tank.  Any 
>  remarks?

If your tank is heavily planted and well lighted, it won't cycle.  Your plants
will consume ammonium before it can build up, so you won't notice the ammonia
build-up that occurs when you rely totally on a bacterial bed for ammonia
removal.  If you have a bacterial filter installed, you may notice a slight
rise in nitrates over a few months, but if your tank is planted heavily enough
and has few enough fish, the nitrates shouldn't build up.

I don't think the feeder shrimp should cause a problem.  The worst thing they
could do is die.  My 20g+5g (5g in a 10g sump) has 7 ottos, a half-dozen
shrimp, 3 adult platies, a dozen juvenile platies, and several dozen baby
platies, plus 6 apple snails and who knows how many ramshorns.  I don't feed
them often, and they graze on the algae all the time, keeping it well under
control.  This tank has 80W of light, is very, very heavily planted (It's
holding all of my plants while I set up my 55g again), and has not bothered to
cycle since I set it up a month ago. 

David W. Webb
Enterprise Computing Provisioning
Texas Instruments Inc. Dallas, TX USA
(214) 575-3443 (voice)  MSGID:       DAWB
(214) 575-4853 (fax)    Internet:    dwebb at ti_com
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