Turns in Reactor Plumbing and Flow Rate - The Planted Tank Forum
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post #1 of 4 (permalink) Old 06-03-2014, 05:06 AM Thread Starter
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Turns in Reactor Plumbing and Flow Rate

I'm building a Griggs reactor. After flowing downward through the reactor, the water flow has to do reverse direction to get back up to the aquarium. Is it reasonable to do the 180 degree turn in the same 2" PVC as the reactor body in order reduce head loss compared to doing the turn in 1/2" tubing?

Here's what I mean:

I haven't glued anything yet. Ideally, I would just use the clear PVC and two straight barbs, then do the turns with large radii using tubing, but my cabinet space is limited. I also have a 90 degree barb which I could attach to the bottom of the reactor if it turns out doing the turn in 1/2" tubing would be more efficient.
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post #2 of 4 (permalink) Old 06-03-2014, 05:12 AM Thread Starter
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Here are two other configurations I could do:

Now that I think about it, I could just put this thing in a bucket so it doesn't leak everywhere and stick the output of my filter on one end and measure the flow for all three configurations. I will do it this weekend and post the results.

Last edited by tenthe; 06-03-2014 at 05:26 AM. Reason: idea
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post #3 of 4 (permalink) Old 06-03-2014, 05:55 AM
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If I were to make a reactor, I would want a little bit of restriction in the outflow because it increases chamber pressure which helps increase the rate of dissolution. A very tall head height can also accomplish this since the weight of water in the return tubing will exert pressure.
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post #4 of 4 (permalink) Old 06-04-2014, 03:14 AM
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I would see no reason to go with the larger pipe turned back upwards. Once any bubbles reach a point where they are going up with the flow, they will quickly move on up and out to the tank. I find it very nice to have a flat bottom to set the reactor on rather than have fittings there. To avoid this I use a tee at the bottom end with a flat plug rather than a cap. Then I go with the adapter to get down to a barb fitting.
I find the restriction to flow is not so much from the turn, although that does add to it, but looking at the ID and OD sizes. With 5/8 iD tubing putting a 5/8 barb sounds like keeping the same size. But in fact a 5/8 OD barb has much smaller ID size. We go from a size that we can almost fit a thumb in down to a size that a little pinky won't fit?
If it was a highway, going around a curve slows it down but the fitting works like going from 4 lanes to two.
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