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Re: [APD] RE: CO2 Saturation

I'll help cover the rest of 'the page.'

I recently built and posted about a reactor, and so far I think I have a
faulty design of which no one is to blame. :-(  The design is pretty simple,
merely the original gravel vac tube from my python filter, some 90 degree
pvc fittings and other misc. parts plus a handful of bio balls.  Ok, not a
faulty design, maybe my pump is just too strong?  I have a 750gph sump pump
pushing up 1', where it then goes thru a 90 degree then down the gravel tube
filled with bio balls (the 90 degree fittings are filled as well).  At the
bottom there is one 90 degree pvc to a few reducing fittings then back up
again about 2.5' to the bulkhead where it goes up another 2' to the nozzle
in the aquarium.  I'd say it pumps far less then 500gph with this head.
I've been steadily increasing bubble rates, and am now at about 3
bubbles/second.  The dissolved CO2 in my tank barely reaches over 15ppm by
morning just before the lights turn on, and is below 7ppm at night just
before lights out.  I noticed depending on where I put the CO2 it has the
possibility of being pumped into the tank about 1/3 bubble size or so,
floating to the top and POP, there goes the CO2.  I'm worried if I put the
CO2 line at the bottom of the reactor to follow the proper design the bubble
will simply be pushed out (and rather easily) the reactor and into the tank,
plus it's going to take some drilling/sealing to get that done.  I
originally had a tap in the nylon return tubing before the reactor, that
didn't work well at all, bubbles just went into the tank.  I then thought
perhaps if the bubbles were smaller they'd have more time in the reactor, so
I then put the line back near the pump impeller where I had it before the
reactor.  This resulted in a fine mist much like before, only the CO2 levels
were slightly higher.  I wonder if with this design I'll ever be able to
achieve the rates (~30ppm) Tom has suggested to me...any ideas?

90G all-glass w/overflow, glass canopy, two Custom Sea Smart Lamps, 48",
2x2x65W, home made wed/dry filter (5G bio balls), home made reactor, pmdd
~5mls/day, KH 4, GH 4, pH from ~6.8-7.2 :-(

Also, pearling.  I know it's something people look for, but I just have
plain never seen it unless I'm doing a water change (aerated water).  Could
there be something else I'm missing?  Perhaps it's related to the
lower-then-standard CO2 levels?


----- Original Message ----- 
From: "S. Hieber" <shieber at yahoo_com>
To: "Aquatic Plants Digest Messages" <Aquatic-Plants at actwin_com>
Sent: Friday, February 27, 2004 3:15 PM
Subject: Re: [APD] RE: CO2 Saturation

> Your CO2 levels are fine, you say -- I assume that means
> about 20 ppm) so you don't need more CO2 going onto the
> aquarium. So more water flow is the next thing to try after
> putting something in the reactor to diffuse the water
> current.
> On a 30 gal aquarium, I have a Rio 180 on 2" diameter by
> 12" long external reactor -- a T. Barr special btw. The Rio
> is rated for 80 gph against 1 ft of head. But it's probably
> pumping closer to 40 gph than 80 gph in this setup. The
> aquarium has a glass top and I run about 12-15 bubbles per
> minute to maintain a 20+ ppm CO2 level. So it can be done
> without a lot of water, CO2, or a large reactor for an
> aquarium around that size. The less CO2 you drive off, the
> easier it is to maintain 20 ppm in the water.
> Hopefully, others will post, too, and you will see that the
> CO2 flow rate and the water flow rate tends to be all over
> the page because things differ from setup to setup.
> However, a couple hundred gph should be plenty for most
> situations, but of course, it depends on tank size. The Rio
> 600 is rated for a max of 200 gph so it probably puts out
> about 100 gph in most situations that don't have high
> dynamic head -- like pushing water 3' or 4' uphill. You
> might be better off with a Rio 1100, which is rated for a
> little over 300 gph. If the flow is too high you can
> throttle down the water flow with the valve that Rio
> includes with it's pumps/powerheads. I say this because I
> don't know all the specifics of your situation and it's
> easier to buy a bigger pump and throttle it down than to
> buy a little, find it's too small, get a bigger one, find
> it's too small, get another etc until you find  the right
> pump/flow. The diff in price is probably about $10.
> The only advantage of an external reactor is that it's not
> in the aquarium and it gives the CO2 no way out except as
> dissolved in the water. In fact, if you could seal the top
> of your gravel tube and seal the bottom, and have a fitting
> top and bottom so you could put it outside the aquarium,
> that would be an external reactor. I'm not recommending
> doing that with a gravel tube; I'm just making a point
> about what an external reactor is -- just a box or cylinder
> with water going in at the top, out the bottom and CO2 fed
> into it. I think the advantages are big ones but they
> aren't really all the diff mechanically than the reactor
> you have now. Not having a large open bottom, externals
> tend to make it a bit harder for bubbles to be flushed out
> with the water flow -- except when the flow is very strong
> and the reactor is too narrow or too short or both. A 3"
> diameter by 14" diameter reactor should bable to handle 300
> or more real gph and maintain levels in a 200 gal or so
> aquarium. That's jsut to give yo an idea of how far you
> don't need to go -- unless you've got a really big aquarium
> or are driving off CO2 with a biowheel, or some such thing.
> How big is your aquarium, how tall, and how long is your
> gravel tube? A longer tube will reduce the amount of CO2
> that gets out the bottom and should increase the exposure
> of incoming water to the CO2 rich environment inside the
> tube.
> Hope that helps,
> Scott H.
> --- Steve <steve_wilsonii at fishpalace_org> wrote:
> > Thank you for your replies.
> > Scott, I notice much more pearling with my noisy
> > powerhead then my 2224. If I put an external
> > reactor reactor on, will the 2224 have enough
> > power to do it properly?
> > If not, is the Rio 600 the best choice for a
> > powerhead. I have a local shop that has a range of
> > Rio models. The noisy powerhead has to go...
> > I do use eheim filter pads cut to fit my reactor
> > to break up and hold in bubbles. Just looking for
> > some better options. My CO2 levels are fine in the
> > water...
> =====
> S. Hieber
> -  -   -   -   -   -   -   -
> Amano Returns
> to the AGA Annual Convention
> Nov 2004 -- Baltimore
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