reactor - high or low flow?
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Old 04-24-2013, 02:28 PM   #1
WheeledGoat
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reactor - high or low flow?


I'm in the process of designing myself a manifold, inspired by this creative genius.

I love the parralel design which will slow the flow and improve the effectiveness of the heater and UV light - but does the same apply to the co2 reactor?

My gut says that I want to maintain high flow through my Ista Max Mix reactor. This is based on the observation of co2 buildup at the top of the Ista when I turn my pump down. But so long as I keep the flow maxed coming out of my 206, there's no co2 buildup. (currently everything is in series).

So I'm thinking about putting the heater and UV light in parrallel, and then the reactor after they join back up, in series. I'm going through great pains to come up with a design that eliminates 90 degree elbows to help my poor 206 with flow...

But I keep flipflopping on the theory of what kind of flow I want through the reactor. Fast for more turbulence? Or slow for more time to dissolve? Please offer your thoughts, I've confused myself...
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Old 04-24-2013, 02:44 PM   #2
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I definitely wouldnt put high flow through that reactor. It was exactly what I used to use. Until 25 gallons of water ended up on my floor..

Do yourself a favor, buy or build a better reactor
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Old 04-24-2013, 03:45 PM   #3
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where did it fail? and which would you recommend?
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Old 04-24-2013, 03:46 PM   #4
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Default Re: reactor - high or low flow?

Quote:
Originally Posted by msawdey View Post
I definitely wouldnt put high flow through that reactor. It was exactly what I used to use. Until 25 gallons of water ended up on my floor..
No offense but a loose hose isn't a reactor failure. Wasn't this a case of letting excess pressure build up, IIRC?

I've had no issues with max flow from a 2217 on one of those.
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Old 04-24-2013, 04:32 PM   #5
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Just turn up the flow until you have CO2 begin to escape before being absorbed. Then turn it back a notch. Anything more is just wasted energy.

One concern though...if you put your reactor in parallel with the UV, you are in fact adding yet another way for pathogens to bypass the sterilizer (the whole tank inlet/outlet process is the primary way).

In my mind, since dwell time in the UV is more important (and less flexible in design), I would design the CO2 reactor (vary length rather than flow) around the UV, and not do the parallel configuration.

Last edited by nofearengineer; 04-24-2013 at 04:38 PM.. Reason: Additional thoughts
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Old 04-24-2013, 06:02 PM   #6
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I definitely appreciate the input - but my situation seems to be opposite from what you say:
Quote:
Just turn up the flow until you have CO2 begin to escape before being absorbed. Then turn it back a notch.
I never have co2 escape, but I do get co2 buildup in the top of my reactor when my flow is too low. Running my filter on max flow is the only way to prevent the buildup.

The main reason I want to switch from everything being in series to using a manifold and running some components in parallel is to cut down on the resistance and hopefully improve the flow coming out of my 206... so I'm going to great lengths to eliminate elbows and long lengths and make it as tight as possible.

I agree that the UV light would ideally treat 100% of the water, every pass through - but slower flow is better for UV. I see my choices as:
-Run parallel, slower flow: full treatment on what water does flow through, keeping the population of undesirables below a certain percentage, if not at 0.
-Run series, fast flow: partial treatment on all water. Maybe it's the pharmacist in me, but I can't help but see this as a setup for selectively breeding the heartier organisms, killing only the weaker ones with brief (inadequate) UV exposure.

But again, I definitely appreciate the viewpoints expressed. Not trying to argue, just trying to sort it all out to a point that makes sense in my own head and build the manifold that works for me...
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Old 04-24-2013, 07:17 PM   #7
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Have you tried not running your CO2 reactor in the vertical position?

By tilting it, you can achieve much the same result as lengthening it.
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Old 04-24-2013, 07:28 PM   #8
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Quote:
Originally Posted by nofearengineer View Post
Have you tried not running your CO2 reactor in the vertical position?

By tilting it, you can achieve much the same result as lengthening it.
and what "result" is that? you're losing me somewhere here.

Do you realize that the Ista Max Mix reactors' exit tube extend to the bottom (when oriented vertically) to reduce the likelihood of putting out undissolved co2? Turning it on its side would seem to circumvent that. Also, I wonder how well the impeller will operate on its side.

or maybe I'm just not understanding where you're coming from at all...
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Old 04-24-2013, 07:41 PM   #9
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What I'm saying is that, when your reactor is in the vertical position, the bubble, responding to gravity, climbs to the top rather quickly, even against your water flow. Which is why you are asking about increasing the flow, right?

To make matters worse, after it has accumulated at the top, the surface area available for diffusion is only a circle the size of the inner diameter of your reactor. Not a lot of area.

If you were to tilt the reactor it to 45 degrees, for instance, the bubble doesn't try to get to the top as fast. Since your reactor is see-through, you should be able to find an angle at which the bubble never even reaches the top.

Even if some CO2 does accumulate, it will now fill a long, elliptical shape, with a lot more surface area. That would help diffuse it faster and reach some sort of equilibrium.
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Old 04-24-2013, 07:49 PM   #10
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ahhh... sorry, thanks for spelling it out. as it turns out, I do already have it optimally tilted as you describe.

my motivation for optimizing the current through my devices and maximizing flow is for the ultimate end of more water movement in the aquarium itself. right now it's rather pitiful. i have a thin film on the opposite end of the aquarium from where the output is... not even strong enough to keep the surface agitated along the length of a 29gal!
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Old 04-24-2013, 08:41 PM   #11
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Regarding the issue of running the UV filter in parallel vs series, i think there is some fuzzy logic going on. Here is my .02. Keep in mind that I have never owned a UV filter, so these are just ideas . . .

Any time you pull water from a tank, put it through the UV filter, then put it back in, you will never filter 100% of the water. (nofearengineer already alluded to this issue.) As you increase the flow rate, you will get closer to filtering 100% over a given time period, but you will never reach 100% because you will always be drawing from some mixture of filtered and unfiltered water in the tank.

If you want to maximize the effectiveness of your UV filter, you need to set it up so that the flow rate is as high as possible without exceeding the flow necessary to achieve an effective dwell time within the filter. The only exception to this would be if you somehow made the manifold (or inlet and outlet placement in the tank) such that water drawn into the UV filter was collecting a disproportionately high mixture of water that had already been filtered. (ie, the manifold was pumping water in circles, or outflow was pointing directly into in the inflow in the tank). As long as the manifold is designed right, I don't see why water would flow in circles, but I bet it could be done . . . venturi effect or some such issue?

One caveat is that if your inflow and outflow are thoughtfully placed, you may actually be benefitting from the opposite of the effect described above. If you are drawing water from the tank that is mostly unfiltered (not just a proportionate mixture), then some of this benefit is lost by running in parallel.

My guess is that in a tank that is as turbulent as most well-filtered tanks, running a UV filter in parallel would be just as effective as running one in series. And if you were able to achieve a more optimal flow rate by running it in parallel, then it would be more effective.

Just my thoughts. BTW, glad you like the manifold design!
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Old 04-24-2013, 09:17 PM   #12
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Thanks for weighing in, ETK!

what do you think about the reactor, though? high flow (series) or slower flow (parallel) for optimal operation? I see you have a large model of the Ista, or at least you did...
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Old 04-24-2013, 10:35 PM   #13
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Quote:
Originally Posted by WheeledGoat View Post
Thanks for weighing in, ETK!

what do you think about the reactor, though? high flow (series) or slower flow (parallel) for optimal operation? I see you have a large model of the Ista, or at least you did...
hmm, hadn't noticed before, but since you are running a Fluval 206, i think you want all the flow through the reactor . . .

Right now I have half the flow going through the Ista reactor, and half going through the inline heater. Both individual ball valves are wide open (four really, since they are top and bottom), and the bypass ball valve is closed. But that is using an FX5, which has a pump that is about 4 times as strong (if i am reading the specs right).

BTW, what size is your tank?
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Old 04-25-2013, 12:30 PM   #14
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Yeah, the flow out of this 206 was fine at first for my 29gal - didn't quite have it maxed... but since I've put all these devices in, it's definitely lacking.

There's room for improvement though. I haven't given up yet. Before I go get a 406 I'm gonna clean things up, get rid of some excess tubing, eliminate the ribbed tubing entirely, and put a couple things in parralel with a smooth-as-possible manifold.

I'm even thinking about mounting the devices to a board or something and curving tubing from one to the next with Y-splits, instead of using 90 degree PVC elbows.
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