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RE: DIY co2 having no effect

Carla wrote.............

Date: Sun, 28 Mar 1999 20:37:18 EST
From: CarlaThorn at aol_com
Subject: DIY Co2 having no effect

Could anyone tell me why Co2 injection in a 55-gallon tank would have
practically no effect on the pH or plant growth? I have 3 bottles going at
once--two 3.8 liter bottles and 1 half that size. All filled with the usual
combinations of water, sugar and yeast and bubbling like mad into bell-type
diffusers. (I've also tried airstones and feeding tubes into the intake of
two-biowheel wet/dry system.) The only surface turbulence comes from the two
biowheels, but it's hardly a ripple. All tests look good (nitrate, ammonia,
and nitrite not detectable; only phosphate is high, but I just added a
to bring that down). When I first tried injecting Co2, my 7.5-80 pH came
to 7, but bounced back up to 7.5 and has been there ever since. What gives?

Carla I would suggest the bio-wheels are out-gassing more Co2 than you
think.  From my own experience with  a bio-wheel  60 (two wheels), on a 30g,
I can definitely say that you are loosing lots of Co2.  Even if you keep the
water level in the tank right up to the lip of the outflow on the bio-wheel,
most of the out-gassing is happening (IMHO) at the spray-bar and as the
bio-wheel turns and splashes water down into the tank.   Let's face it,
MarineLand did not have planted tanks in mind when they designed these!
They were designed to increase surface area for oxygen-starved,  cycling,
bacteria in order extend larger fish loads per gallon of water.  And they do
a great job at this.

You may want to remove it temporarily and see for your-self.  Pull the
bio-wheel off and watch what happens!   Three DIY Co2 systems on a 55g  may
drop your pH quick w/o the right buffering. So make sure your kH is up
around 3-4 minimum using baking soda (~tsp per 30 will raise it 2 kH, in my
tank anyway).  If the pH starts to drop to fast/to much, point a powerhead
or your filters outflow to cause a little ripple on the surface, then back
it back down after a while and see where your buffering/pH settles in at..
it's the kH/pH dance.  A successful tank owner knows his water's buffering
and just what is needed to get the right kH/pH/Co2 injection rates to make
fish and plants happy.  Not everyone starts out doing the Tango.  I'm about
at the watusi-level.

My 30g system now runs with NO Bio-wheels, injected Co2 (a ~1 bubble every
1.5 seconds), kH 2-3, gH 2 and yields pH of 6.4 right out of my well.
During peak photosynthesis my pH actually climbs to about 6.8 (and would
climb higher without injected Co2),  by late afternoon.  After taking the
bio-wheels off I noticed no appreciable increase in ammonia, nitrites or
nitrates, even with 2 3.5" discuss in the tank with moderate feeding.   I do
80% water changes at least once a week or more if I see any algae starting
to take hold and clean/change the filter floss in my magnum canister about
once a month.  Although so heavily planted that the discuss are petitioning
the fish-rights groups because their is no room to swim, I have since never
worried about the plants not handling the bio-load.  I have  80w of tri-phos
and sunshine normal florescent and use varying amounts of PMDD.  I push this
tank to run at a very high "metabolic rate". Light, Co2, fertilizer, plants,
fish-load, snails and water changes are tuned just right but only after a
year or so of tinkering with it.

My guess is without the bio-wheels you will get better plant growth that
will handle (if not more efficiently),  any Nitrates/Phosphates your
fish/feeding regimen is producing and you will be trimming more plants they
you know what to do with!

Remember your fish should leave the dinner table slightly hungry.   FEED
SPARINGLY with various live/flakes/pellets, add trace nutrients in smaller
amounts more frequently (like K, FE),  know you water and change more than
you think you need to, and relax and enjoy the Zen of Aquascaping.

Best Fishes (and plants)
Tom Brennan