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Rex grigg style reactor on mini canister

3K views 18 replies 7 participants last post by  kevmo911 
#1 ·
Has anyone tried a Rex grigg style reactor on a zoo med or toms canister filter ? What size pipe did you use? Is it efficient ? Any pictures you can share ?
 
#2 ·
I've stalled on responding waiting for somebody who has used one on a small can. I've not!
I might throw some general thoughts your way. If it is the amount it might restrict flow, I can't say much but as to sizing, I do have some ideas. If you look at how the CO2 is absorbed in the water, it has to come in at the top and stay in the reactor long enough for the bubbles to get small enough to not continue going upward against the water flow. What this gives me is that the size is not critical on the too big side but really can make it fail if too small. We all like small equipment but this may be a case where we might get it too tight. Too small and the bubbles may not dissolve fully and come out in the tank. Too large and they just go round and round and become part of the water, which is ideal. I use 11/2" and 18-19" long for my 2217 filters so I would think 11/2 X 15-16 might be good for your smaller filters. It might be possible to squeeze that length but I would not want to undersize it.
 
#4 ·
Thank you Rich, maybe 1" tubing would be enough at about 12-15" long.
I think the hardest part will be getting the parts to reduce it to fit the filter tube and C02 tube. I will give it a go and report back once it's been tested.
I guess I could just stick the C02 tubing straight into the canister inlet tube
 
#5 ·
If you are building the reactor, I like just sticking the tubing in a hole drilled in the reactor pipe. If you drill the hole smaller than the tubing so that the tube has to be forced through the hole, it seals itself very nicely. This is the way Rex Griggs designed his. If you do this a trick helps a lot. Cut the tube at a sharp angle and drill the hole near enough to one end so that you can force the sharp point in as far as it will go and then reach in with longnose pliers, etc. to grab it and pull it through.
 
#6 ·
I did one a long time ago , The best thin to use is Polycarbonate Tubes if you can find where they sell Plastics , Just to show you what it looks like :
http://www.tapplastics.com/product/plastics/plastic_rods_tubes_shapes/polycarbonate_tubes/276
You should find it local it's a little more money and a lot stronger , you can drill into it , I used a tap on the side with out any damage or crack for a hose barb for my co2 {I did use small bio balls my self but you don't need it} I use pvc reducer from 2 in down to 5/8 or you can go 3/4 inch hose barbs on both ends .
I also use Weld-on 16 to seal the pvc to the polycarbonate tube and never leak and the tube stayed nice an clear for a long tim witch others will scratch and dull out over a year. This is a out dated forum that I got my info's
http://www.plantedtank.net/forums/showthread.php?t=11707
The one I build was like #2 by Ibn :
http://www.plantedtank.net/forums/showthread.php?t=12331
 
#7 ·
You want to keep the bubbles in suspension without blowing them out of the reactor like Rich said above. The main player here is the water velocity in the tube, larger diameter pipe = slower, smaller diameter pipe = faster. Too slow and the bubbles don't really "dance" up and down in the reactor. Your goal is to keep a lot of bubbles in suspension in the reactor. I run a 2" diameter with a 2217 and it's a pretty good fit, a few tiny bubbles might blow out if I have the filter running wide open. I don't run pads in my canisters, just bio balls so the 2217 is probably hitting just shy of 200 gph wide open. I do run it throttled back a bit to keep the bubbles from escaping the reactor, so maybe I'm at around 160 gph. A lot of fuzzy numbers here, but they should be close enough, we're not building a piano. The Tom rapids is supposed to do 80 gph, roughly half of what my filter is doing. So, you should see a similar "dance" to what I'm seeing in my reactor if you use a reactor with half the cross-sectional area. My 2" pipe has an area of 3.3 square inches, the closest to half of that would be 1.25" OD pipe with an area of 1.5 square inches. My best guess anyways. Let us know what you come up with and how it works out.
 
#8 ·
My main thought is that it is a problem to undersize but rarely a problem to get it too big--- if you have space. If you are really restricted so that using 1" versus 11/2" it may be worth taking the risk of it not fully doing the job, but how often is it that tight? I recommend going big as space allows and then if/when you want to move or change tank or filter size, you still have a reactor that works. The difference in price is so small that I don't consider it worth the risk of not being happy with the result.
Would you want to buy a pair of shoes that were too small because they were on sale?
 
#9 ·
I went to lowes today to buy the fittings and unfortunately they didn't have the correct reducers to go from 1" so I decided to go 3/4" .... It maybe too small but I will give it a go. I think the worst case scenario will be that the bubbles will spend less time in the reactor and make the tank look like a shaken up can of soda .... I will report back once I set it up tomorrow and left it to run for a couple if hours.
 
#10 ·
The odd thing about shopping for reactor parts is that you are likely to have to go to two or more sections in the store. 11/2 " pipe and reducer to get it down to 3/4"NPT are likely to be in the plumbing section. Then to find the 3/4 male threaded NPT to barb fitting, you may have to go to the section where they have all the small brass and plastic parts or possibly the irrigation section. You may have to screw grey plastic into white to get it. It is often there, but they may not know it so you have to just stroll around like shoplifting!
I swear I've spent more time in Lowe's than some of the employees>>>>ARRRGH!
 
#11 ·
Ha ha it's funny you say that because the whole time Im attaching parts to parts I thought "I look like a shoplifter" lol
The reactor has been running for a couple of hours now and at about 35 mins the drop checker had gone light green and the Anubis are pearling. I'm running 1bps so it seems pretty efficient compared to me running the co2 tube straight into a Hagen mini filter like I had been doing previously.
If I was to do this again I would use 1" pipe instead of 3/4" because I do see tiny bubbles coming out of the spray bar and I think 1" pipe would dissolve the bubbles much better, however I think the bigger pipe would make you lose the desired flow rate.
 
#18 ·
A little late in the game, but if what you're trying doesn't work out, you might want to consider an in-tank venturi reactor. They add some gear to the tank, but they're good for smaller sizes.

http://www.plantedtank.net/forums/showthread.php?t=35198

The venturi system would require a water pump though. Another way is to feed back the excess CO2 near the surface of the reactor to the tank water itself. Just attach a CO2 tubing from the top of the reactor and feed it back to the tank water.
 
#13 ·
I jist built my rex griggs for a fluval 406 and the low was cut in half I also negated the instructiins for it beong under 22inches and forgot to cut the sch 40 in half sooo I went with it all 30" I doubt size matters in this case and may cut mine down and use a female _female to shorten it some to 18"
hope it brings my flow up some more
 

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#15 ·
good cause i dont need the 90* i was following reactor plans i left my common sense at the www... lol that makes sense also the hose attached needs a nice soft bend the one on it had to be ziptied to keep it close to the tank top . its in the works next week . thanks for the tip
btw the wife said lets lay it down on top the cabinet in otherwords its too big
 
#16 ·
You might need to tel the wife it won't work that way! The point of adding the CO2 at the top is so that is will try to float up against the current. If it is laid flat, the bubbles can easily move along and back into the tank before the react.
On the flow question, water is sometimes like traffic. If you were driving through the reactor, think where traffic would be slowed?
 
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