Why Not higher CO2 levels w/pressurized setup?

[br1dge]

I just finished a weekend of setting up a new planted tank. I decided on the internal powerhead driven reactor found in the image library here. Can those of you with similar setups and more experience please "check" my expectation level. And for now, PLS do not recommend a different reactor/diffuser setup. I'd like to get all I can out of what I currently have before trying new/better ideas.

Did I build mmy reactor right? Is it working properly? I have yet to see a "bubble" at the top of the reactor, but I do have very fine bubbles floating through out the entire aquarium. Isn't 4 bubbles per second a high "flow rate," and shouldn't it yield a higher CO2 rate than 20ppm? I feel like something is not running efficiently..

Tank Parms - 42G Hex, eco-complete substrate, 4 bubbles per second into reactor. (2) 65W compact flourecents - 280 Emperor HOB filter (with high water level in tank, there is very little splash) Reactor design in picture below

Water Parms
Temps = 81, GH =3, KH = 4.5, pH 6.8 - 6.9 (which equals ~ 20ppm CO2 according to charts) - Using Laborette test kit with liquid reagent.

 

[Tom Barr]

Re: Why Not higher CO2 levels w/pressurized setup?

Rather than blasting the water straight down from the powerhead into the tube, add a 90 degree angle inside the top of the tube so the water flow produces a downward spiral, this will waste less gas and still allow the finer mist to leave the botton of the reactor.

2 bubbles/sec should be enough for a 42 gal hex.


Regards,
Tom Barr

 

[br1dge]

Re: Why Not higher CO2 levels w/pressurized setup?

The way the tube is built, a 90 deg angle is not feasable.. Could a sponge filter or something else be used towards the top of the tube? I assume the point is to create turbulence..

 

[Watcher]

Re: Why Not higher CO2 levels w/pressurized setup?

Wouldn't a 90 degree angle be more likely to produce a horizontal spiral (if a spiral at all) rather than a downward spiral?

I'm setting up my CO2 diffusior (PVC pipe personal set up) to be at a downward (roughly) 45 degree angle to try and get the best CO2/H2O mix. But it's the largest unknown for me if this particular set up will work, or not leak, or severley repress filter flow, or a host of other possible situations...

 

[srozell]

Re: Why Not higher CO2 levels w/pressurized setup?

Wouldn't a 90 degree angle be more likely to produce a horizontal spiral (if a spiral at all) rather than a downward spiral?

The water has to go somewhere, so yes, it is a downward spiral.

 

[Tom Barr]

Re: Why Not higher CO2 levels w/pressurized setup?

The way the tube is built, a 90 deg angle is not feasable.. Could a sponge filter or something else be used towards the top of the tube? I assume the point is to create turbulence..

Oh no, 90 degree elbows of any material is feasible
Much wiser than a sponge, see issues with plant guild's reactor.

A simple piece of vinyl tubing squeezed in there will suffice nicely.
The other thing is to add the powerhead into the side , rather than the top of the reactor tube, the outflow hits the wall rather than flying out the bottom.

The way you have it set up, it'll do about the same as a powerhead alone with the CO2 feed via a small air stone into the suction side.

Regards,
Tom Barr

 

[PaulB]

Re: Why Not higher CO2 levels w/pressurized setup?

Hi Tom, what are the issues with the plant guild reactors???

 

[alexperez]

Re: Why Not higher CO2 levels w/pressurized setup?

One issues I had when I used 2 plant guild reactors, was having to clean the sponge all the time. Till I added a 90 degree elbow (saw on this site) and got
rid of the sponge.

 

[Tom Barr]

Re: Why Not higher CO2 levels w/pressurized setup?

Wouldn't a 90 degree angle be more likely to produce a horizontal spiral (if a spiral at all) rather than a downward spiral?
QUOTE]

The water has to go somewhere, so yes, it is a downward spiral.

Yep, it'll hit the side of the tube. Anmy other angel than 90 degrees, it';ll cause a spiral, if you adjust the 90 degree elbow, you can maximize that.

Regards,
Tom Barr

 

[Watcher]

Re: Why Not higher CO2 levels w/pressurized setup?

Ok, maybe I am not understanding. I believe that straight up and down is zero degrees. 90 degrees is flat on it's side. Crude picture attached for a 90 degree setup. If the water is moving from a flat direction from one side to the other, where does the "downward" spiral come from?

 

[fosteder]

Re: Why Not higher CO2 levels w/pressurized setup?

the reactor Tube should be vertical. At the inlet (inside the reactor tube) there should be an elbow pointing horizontal. The outlet is vertical. If you are pumping water in (even if it is perpindicular to the flow) the water will leave at the exit. It has to go somewhere.

 

[turbomkt]

Re: Why Not higher CO2 levels w/pressurized setup?

Ok, maybe I am not understanding. I believe that straight up and down is zero degrees. 90 degrees is flat on it's side. Crude picture attached for a 90 degree setup. If the water is moving from a flat direction from one side to the other, where does the "downward" spiral come from?

90 degrees is the offset of the input to the reactor. While the reactor tube would be oriented vertically, the inlet from the reactor would be at a 90 deg angle to that...and therefore pointing at the side of the reactor tube. If it can be offset from centerline (let's add one more 90), meaning shifted sideways so that the outlet is closer to the side but pointed in the original orientation, it will induce a swirl. Did I cloud things up any more?

 

[lhforbes]

Re: Why Not higher CO2 levels w/pressurized setup?

Two things:
The picture you drew is 180 degrees. For 90 degrees think of the corner of a square.
I also had the same filter as you on a 30 gallon and had the same problem, CO2 at around 20 ppm, I removed that filter and replaced it with a cannister and my CO2 ppm went immediately to the high 30's low 40's. I think that the wet/dry portion, since it exposes the water to air, is where your CO2 loss is coming from.

 

[Tom Barr]

Re: Why Not higher CO2 levels w/pressurized setup?

Ok, maybe I am not understanding. I believe that straight up and down is zero degrees. 90 degrees is flat on it's side. Crude picture attached for a 90 degree setup. If the water is moving from a flat direction from one side to the other, where does the "downward" spiral come from?

The reactor tube it self is verticle, up and down.
The inlet where thw water comes into the tube is deflected 90 degreres, so instead of going straight out the other end, it hits the side (at a 90degree tangent) and spirals. This reduces the flow and increases contact time inside the reactor tube, without the need for a sponge to save the mist, but then again, you do not want to save the mist anyway............

I'd suggest doing the mist method personally, simpler and easier to DIY and change to.

The results are better also.

Regards,
Tom Barr