CO2 Return Nozzle and Checker

klolyn

Member
Joined
16 Feb 2019
Messages
38
Location
London, UK
Hi Team,

i have an in-line diffuser....

What depth should the return nozzle be in the tank? it is currently approx 5" from the surface but I could extend the pipe to mid way down (10") - would this help the CO2 absorb better being deeper?

Should the CO2 Checker be in the vicinity of the nozzle area or on the other side of the tank (about 4' away)?

I have a power-head in the tank, opposite end to the return nozzle - to help get the water moving about

What do you think?

Thanks

Keith
 
Joined
3 Jan 2016
Messages
376
Location
Woking, UK
My instinct is that you should position your filter outflow to give you the best overall tank flow, rather than worrying too much about CO₂ dissolution and out-gassing. Putting the outflow lower might well result in the CO₂ being retained in the tank slightly more, but that’s no good if the lower position results in dead spots where CO₂ and nutrients won’t reach. The ideal position is difficult to say in general, although we might be able to offer suggestions if you post a picture of the whole tank. You need to take into account the shape of your tank, and the position of any hardscape and plants.

In my opinion you want the drop checker to give you the “worst case” indication, in other words place it where your CO₂ is likely to be at its weakest. You can experiment by putting it in various places and see what different results you get, but the chances are you’ll end up putting it at the opposite end from your filter outflow. I also put it low down, especially if you have carpet plants - you want to know that they’re getting the CO₂ they need. In a large tank, consider having more than one drop checker.

You mention having a power head at the opposite end to your filter outflow. Is it also pointing in the opposite direction? If so I’d reposition it near your filter outflow and pointing in the same direction, so that the two flows add up rather than counteracting each other. Avoid having filters and power heads fighting against each other! Remember, you don’t want turbulent flow (which will happen where two opposing water flows meet) because this is where the water’s energy is dissipated and flow stops; ideally you want a nice smooth “laminar” flow that reaches the whole tank.
 
Last edited:

klolyn

Member
Joined
16 Feb 2019
Messages
38
Location
London, UK
Thanks, i will move the PH across next to the outflow. i may try putting the outflow a little lower and put the PH above it and get another DC to sit at the opposite end of the tank

Keith
 

klolyn

Member
Joined
16 Feb 2019
Messages
38
Location
London, UK
DF456BF5-9AFE-440C-BB78-3EDE5F51757F.jpeg
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Have move PH above the outlet (top right of overall tank photo)

keith
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