Two co2art questions


New Member
Aug 20, 2020
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Philadelphia PA
1) Drop Checker question - I have just installed my co2art setup (more below on #2) and the pH in my area runs around 7.6. I recognize I am looking for a lime green color in the drop checker, but I'm wondering if the pH of the water has any impact on the color I should expect.

2) I have attached a picture of my current setup (please, no comments about the melted plants I picked up - that's why I am adding co2....) As you can see, from left to right is my fluval heater, the diffuser for the co2 (right in the middle of the screen, followed by the INTAKE tube for the canister filter and then on the right the outflow. I have the outflow currently going into the intake tube because I have been trying to cut down on the speed of the current from the outflow. The drop checker is all the way on the right side of the tank.

As you can see from the picture, the bubbles are going up and then only some of them are getting moved around by the outflow. Some of the others are getting sort of stuck in the current under the heater, and because the outflow is blocked (on purpose) they aren't speeding around the tank as might otherwise be the case.

My question is, do I need to juggle things so that the bubbles are spread out more? Drop the heater? Raise the diffuser? Flip the outflow and inflow tubing?

View attachment 814413


Fish Connoisseur
Apr 29, 2012
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Hokitika, New Zealand
Why CO2 for this tank. What is your lighting and it's schedule. Remember Aquatic plants are weeds and really have very simple requirements.


Fish Aficionado
Oct 28, 2006
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Kent, UK
Drop checker:
Are you using 4dkh solution in your drop checker along with the PH regent?
If you are not then you are are not properly measuring your CO2, if you have fish in the tank and aren't measuring your CO2 correctly stop using it for now.
If you are using 4dkh solution then the natural PH of your tank water doesn't matter.

Water Flow:
This is a common trap people fall into when they first get into using CO2. You don't want to restrict water flow. In fact you want as much water movement around the tank as you can get. However you want to direct it so that it is sub-surface so your not off-gassing all your CO2.

Personally I recommend having a spray bar along the back of the tank close to the substrate. This helps get good water circulation around the tank which in turn means nutrients get good distribution.

If not using a spray bar I always try and have my input and output for the filter on opposite sides of the tank. This way you don't get dead zones build up.

CO2 Diffusers:
I have used a bunch of these types of diffusers. In my experience they are all rubbish. It does a terrible job of actually getting the CO2 absorbed into the water and is basically an expensive airstone.

Personally I run my CO2 into the output tubing of my filter. I then cut a bit of tube up into spirals/tassels and stick them up the tube just after where the CO2 goes in then I put on the spray bar a bit further down the tube.

In my experience this gives 100% CO2 absorption, it doesn't cost anything and it then equally distributes it around the tank. you also save a lot of CO2 as you are wasting 90% of it by it bubbling directly to the surface.

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