Another Yugang post

[okcthunderguy]

It sounds like you are either overflowing CO2 too much or otherwise losing CO2 straight through the reactor and out as bubbles rather than allowing it to diffuse into the water. Too strong flow through the reactor is a common problem. THese work so much better with nice slow flow - ideally minimal visible surface disturbance. I'm not sure how the Aqua ROcks Colorado ones plumb in, but putting an FX6 outflow through one of these sounds much too strong a flow without a bypass circuit built in to reduce actual flow through the reactor. I suspect you are blowing quite a lot of CO2 bubbles straight through the reactor without diffusing into the water.
Solutions would seem to be either building a bypass circuit to adjust the water flow through the reactor, or using a much slower pump for a separate reactor circuit

Here's my homemade reactor and bypass cicuit ......

with my fx6, would you think id be better off building a bypass in or my other option I have a spare Fluval 206 laying around that I could run though it separately (could buy a small filter/pump if needed). Heres my tank setup that im trying to do all this on.....

 

[Naturescapes_Rocco]

I'd recommend a bypass! And see my post here about where the bypass should be:

Journal Post in thread 'A New Beginning: 90 P High Energy Tank'

Apr 2, 2026

Not hating at all (you know I'm a big fan!!) but from my understanding of flow, I think this design would work even better if the reactor was in the middle, and the bypass on the outside.

The current design:

Water takes the "path of least resistance", which is mostly through the reactor. Probably 90% of the water flow goes through the reactor no matter what, and ~10% can be adjusted with the valve, in the current orientation, due to friction around the corner, etc. Not all, but most, flow goes through the reactor, so maybe not much can be adjusted with the valve.

If you were...

• Naturescapes_Rocco

• 
• 

You can also run two return lines, where one has a valve for slow reactor flow and the other is fully open for max flow. Two return lines in a tank helps with good circular flow, too:

 

[JayP]

I'd recommend a bypass! And see my post here about where the bypass should be:

Journal Post in thread 'A New Beginning: 90 P High Energy Tank'

Apr 2, 2026

Not hating at all (you know I'm a big fan!!) but from my understanding of flow, I think this design would work even better if the reactor was in the middle, and the bypass on the outside.

The current design:

Water takes the "path of least resistance", which is mostly through the reactor. Probably 90% of the water flow goes through the reactor no matter what, and ~10% can be adjusted with the valve, in the current orientation, due to friction around the corner, etc. Not all, but most, flow goes through the reactor, so maybe not much can be adjusted with the valve.

If you were...

• Naturescapes_Rocco

• 
• 

You can also run two return lines, where one has a valve for slow reactor flow and the other is fully open for max flow. Two return lines in a tank helps with good circular flow, too:

I'm still considering a bypass for my ARC small reactor but the trick on those is finding the best fittings to work with ARC's since they're not standard U.S. sizes other than the barbs themslves.

 

[Naturescapes_Rocco]

I'm still considering a bypass for my ARC small reactor but the trick on those is finding the best fittings to work with ARC's since they're not standard U.S. sizes other than the barbs themslves.

The couplings are 25mm (euro sizing) which you can get all 25mm PVC parts on amazon, OR you can get some 3/4" PVC Union couplings, which will actually fit the existing reactor sizes! I already did this previously and it worked great.

I used these, kept the original "screw ring" from the 25mm size. The flat half of the 3/4" union can sit just fine over the gasketed-side of the existing 25mm union. Tighten them down with the original 25mm screw ring, and you just adapted to 3/4" PVC for your builds.

 

[hamfist]

with my fx6, would you think id be better off building a bypass in or my other option I have a spare Fluval 206 laying around that I could run though it separately (could buy a small filter/pump if needed). Heres my tank setup that im trying to do all this on.....

In truth, either strategy would work. There is actually a benefit of not having the reactor set up on your main canister filter. It the reactor is set up on your FX6 then each time the filter is turned off for tank/filter maintenance/cleaning, CO2 addition to the tank is lost. If you are anything like me then CO2 is timed to be injecting up to around 7pm so if I want to avoid shutting the CO2 off to the tank then I have to do all maintenance that involves shutting CO2 off after 7pm, which is a bit of a pain. I also generally turn my filters off during the weekly tank cleaning/water chnaging session, which lasts around 1-5 to 2 hours. Ideally I wouldn't want to have CO2 shut off for that length of time. So, having the reactor running via a separate smaller filter or pumped circuit that can continue dribbling into the tank during the whole tank cleaning session is still fine.

If building the reactor into a bypass circuit on the FX6 output then I'd thoroughly recommend having the control valve in the reactor side of the circuit NOT the bypass side. It will give you far more control to achieve low flows through the reactor by having the valve in the reactor side of the circuit. If you have the control valve in the bypass side of the circuit then the minimum flow achievable in the reactor is generally only around 50% of the filter output, which may well be more than you want/need trhough the reactor.