[Scheidtman]

Okay, so I decided to make a reactor given that the ones you buy are either cheaply made or made for higher flow than my canister. I know the normal design is with 2" pipe, but since my canister filter (Fluval 204) only puts out 150gph max, I thought it would be better to use narrower tubing. I used 1 1/4", since I already had that and thought it would work. I have it connected and to my surprise it doesn't the flow much at all. I used the biggest fittings that I could find that would work.

So here's my observation, and looking for advice on what size to use on my next attempt. Bubbles are coming out of my outlet and floating to the top immediately, so I did get rid of the "fizz" created by the diffuser, but at the expense of actually absorbing the CO2. It seems to actually be absorbing LESS than with the diffuser. I kept the bubble count the same and kept an eye on it.

So what should I try next, go with the standard 15" of 2" pipe like the design calls for? I was afraid of buildup at the top, given that my output is only 150gph, but it looks like the 1 1/4" has kept the flow too high. Another option would be to add a valve to increase the backpressure?

I should also note that my tank is 29 gallons, fairly heavily planted.

I could also try using this connector at the bottom to add backpressure to the reactor. See pics, much smaller opening.

 

[EmotionalFescue]

I don't think you have to remake this... I think you need to add a reactor bypass so you can reduce the flow through the reactor without limiting the water flow to the tank.

Here's what I would do: put tee barbs on the reactor in and out, then connect them with some tubing and a ball valve.

Like this:

You can then use the ball valve to tune the flow through the reactor.

 

[Scheidtman]

I don't think you have to remake this... I think you need to add a reactor bypass so you can reduce the flow through the reactor without limiting the water flow to the tank.

Here's what I would do: put tee barbs on the reactor in and out, then connect them with some tubing and a ball valve.

Like this:
View attachment 1035964

You can then use the ball valve to tune the flow through the reactor.

I've seen that, but wasn't sure if it would work here properly. I suppose I'd need to find some really big tees as to not restrict flow there. Also, don't I need another valve at the base of the reactor in order to create backpressure in the reactor? I thought maybe if I do that with the reduced connector that I have in addition to the bypass that you have suggested would be best? I've read that backpressure significantly increases absorption. Where does one find a ball valve like that, anyway? I didn't see them at Lowes. I have 5/8" ID tubing.

 

[Scheidtman]

Also, what do people do for bleeding the air at setup and future events where air would get trapped? I thought of maybe just drilling a hole and inserting a screw or bolt.

 

[burr740]

Regardless of gph bigger dia is always better due to more dwell time. If you make it over go at least 2", or 3" if it fits

 

[Scheidtman]

Regardless of gph bigger dia is always better due to more dwell time. If you make it over go at least 2", or 3" if it fits

Yes, but doesn't too big diameter compared to flow (diameter to flow ratio) cause CO2 build up due to lack of circulation? I have heard about this problem, but maybe not the case with this type of reactor.

 

[moke]

Also, what do people do for bleeding the air at setup and future events where air would get trapped? I thought of maybe just drilling a hole and inserting a screw or bolt.

if you're injecting 2-3bps you'll get a build-up of co2 (and other gases) towards the end of each day. pretty much no way getting around it. you could use tom barr's recirculating hack.

 

[Scheidtman]

if you're injecting 2-3bps you'll get a build-up of co2 (and other gases) towards the end of each day. pretty much no way getting around it. you could use tom barr's recirculating hack.

I'll have to look that up. Today I'm monitoring closely to see exactly what's going on as it's the first day it's operating from ground zero. So far just a few bubbles coming out here and there, so it's better than fizz. I haven't put the loop in yet to decrease the flow to the chamber, because I'm waiting on parts for that. This gives me time to see exactly what happens before making drastic changes. So far ~.5 pH drop in the 3 hours since the CO2 kicked on. I imagine the drop will continue slower now since the light is on full bright now? It's at 6.72 at 2.5ppm KH currently. I need to get to 6.4-6.6 according to Rex's chart.

So how quickly do you guys get to CO2 saturation usually? Should I try to get to that point before the lights are on full power?

 

[moke]

So how quickly do you guys get to CO2 saturation usually? Should I try to get to that point before the lights are on full power?

i get ~1.25pH drop within 3 hours. and yes, it should be there by the time the lights come on.

 

[Scheidtman]

i get ~1.25pH drop within 3 hours. and yes, it should be there by the time the lights come on.

When you say 1.25, is that from fully gassed, or what you start from I'm the morning? My .5 that I referred to was from starting point, but fully gassed would be .9 I believe. You must be talking about fully gassed, otherwise that's too much CO2, right?

 

[moke]

yes, that's fully gassed. i have a surface skimmer and quite high surface agitation. takes overnight to off gas the co2 and get back up to baseline.

 

[fpn]

Also, what do people do for bleeding the air at setup and future events where air would get trapped? I thought of maybe just drilling a hole and inserting a screw or bolt.

You could try to increase the efficiency of the reactor by adding a venturi loop, but not sure how easy that is with the canister filter.

Dual venturi DIY External CO2 reactor

This unit cost about 20$ due to using Clear PVC housing, you can use solid 2" pipe if you wish. You can find all the parts at any Orchard Supply Hardware or Home Depot. Two: 2" slip to 1/2 threaded bushing Two: threaded 90 elbow 1/2" barbed About 10 Bioballs if desired 12" of rigid...

barrreport.com

 

[moke]

You could try to increase the efficiency of the reactor by adding a venturi loop, but not sure how easy that is with the canister filter.

Dual venturi DIY External CO2 reactor

This unit cost about 20$ due to using Clear PVC housing, you can use solid 2" pipe if you wish. You can find all the parts at any Orchard Supply Hardware or Home Depot. Two: 2" slip to 1/2 threaded bushing Two: threaded 90 elbow 1/2" barbed About 10 Bioballs if desired 12" of rigid...

barrreport.com

i wouldn't bother with tom's venturi loop and i wouldn't know how to reroute the recirculated co2 in a canister, he really didn't address the issue. i have mine running on closed loop so was able to recirculate what was accumulating, but found no benefit and didn't like the pfft pfft noise as co2 hit the pump's impeller.