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Wrong size reactor for 2217?

804 Views 8 Replies 4 Participants Last post by  mike-guy
I built your standard Rex style reactor using 1/2 barbed inlet and outlets which match my Eheim tubing on my 2217. It's 24in tall with a 90 degree coupler at the bottom to help keep the hose from kinking, 2in piping all the way. From what I read this is about a normal size for my filter, maybe a little longer but length shouldn't affect water velocity right?

The Problem.
I am getting my bubbles from it then I did my intank powerhead reactor. Also I bought white PVC so can't see whats happening but it's making a fair gurgling sound like it's building up co2. The bubble rate is turned down to 2-3 BPS. Super sad right now lol. Over 2 years waiting, 200 bucks later and it's not working like I wanted. The inlet is on the top of the reactor and it sits completely vertically so that is not it, I know that is a common mistake.

Any advice or tips is appreciated.
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Sounds like you might have too much flow for the size of the reactor. If you're getting big bubbles coming out, maybe the flow is too strong, not allowing enough dwell time for the co2 to dissolve inside the reactor before it gets pushed out. You can try closing the double tap a bit on the filter to slow the flow.
Yea I was shocked to think that myself. It's over 30in once you include all the couplers and adapters. It's to late to add bio balls but what could I drop in the 3/4 fittings that would chop them up yet not clog it or blow out.

I will try slowing the flow to see if it helps, although I probably won't be comfortable leaving it this way.
Something really basic has to be wrong. The design sounds good but maybe something in the details. I use a 2217 with about 19 inches of 1/12 inch PVC much like you describe. Main difference in mine is that I'm shooting bubbles way too fast to count on a 75 and a 125. Neither get tank bubbles that I can spot.
Can I ask how and where the CO2 tube is connected to the reactor? Not at the bottom rather than the top? Water flow from top to bottom so the CO2 has to fight the flow while trying to go up against the current? Tubing extends into the center of the reactor rather than dumping along the side?
You are correct in your thought that the length will not change the velocity of the flow. I would assume the extra length would keep it in the reactor longer.
Random thoughts rather than solid ideas.
Using a 1/8 in barbed fitting for the co2 about 6 in from the top. It extends into the PVC very little.
Interesting. I have a 2217 with only 19" of effective reactor length in 2" pipe. Flow enters vertically from the top, exits via 90 degree elbow at the bottom. I also have white PVC so I can't see the bubbles inside the reactor but it's only when I get in the 4+ bps range that I can see the smallest amount of fizz entering the little you have to be watching for it.
I have a hydor inline heater after mine so just a little extra pressure drop with the water finally entering the tank via cheap knock off lily pipes. CO2 enters 5" below the top via tubing that extends halfway into the reactor and is cut off at downwards angle. If your CO2 is entering right at the side of the reactor surface there is very little downward water flow at that point and the CO2 has an easier path to the top of the reactor. Still the water should have enough retention time with the CO2 to begin to dissolve it.

I wish I had an answer for the undissolved CO2 for you but on paper I'd say you did everything correct. Last resort would be to step up the pipe diameter.

My reactor gurgles quite a bit when I restart it. Given 8 or so hours (at least overnight) and I don't hear it anymore.
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Yea it sounds like we have near identical setups. The filter is only a few days old so I do expect flow to slow a little but still suprised I'm getting these bubbles.

I stopped at Lowes and to build a 3in one would cost more then I want to spend. Instead I got a T fitting with a threaded cap I'll put in the one I got and throw some kitchen scrub pads in there. See how it goes I guess.
I'm not sure I would go any larger diameter. I think that might just give more space for the CO2 to build rather than keeping it in the mainstream flow. An easy to try thing might be to rotate and tilt the reactor so that the Co2 is not able to go directly up the sidewall to collect at the top. One of the things I find happening on the Grigg's design is that there are what look like small mods made that turn out to cause unexpected trouble. Using a barbed fitting may be one of those which sounds good but may not work as well as the really simple first design.
Simple way to test if you can get it leaning just a bit and leave it there for some time?
BINGO! Problem solved with the plastic scrub pads. They must be giving the tiny bubbles just enough resistance to break them down. I got of them in the pack and just threw all the in to be sure it would work. I'm going to remove a few and see if I can pick some flow back up. Now only bubbles lowing around in the tank are from my pearling plants (and pearling algae lol). Thanks TPT for your wealth of knowledge
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