Two co2art questions - drop checker and setup

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?

Thanks!

 

Yes the pH has a direct impact on the colour of the drop checker, with about a 2 hour delay. For it to go green your pH will probably need to drop below 7. You can experiment to get the best dispersal and keep the bubbles suspended as long as possible. I found one way was to direct the outlet towards a side tank wall with the diffuser at the bottom. The flow would hit the tank wall and go down pushing the bubbles with it and then along the length of the tank.

 

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.

As I understand it, the concentration of CO2 changes the color, not the pH. But, the CO2 will also effect the pH. So, by the time you have enough CO2 to make your drop checker green, your tank's pH will probably drop by about 1. This should happen regardless of where your pH starts.

2) ...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?

You don't necessarily have to change anything. But, I would move the output and intake of your filter as close to a corner as possible. Your goal should be to get a current that moves from the output all the way around your tank before it goes back to the intake. Try to eliminate as many dead spots as you can. If it doesn't aesthetically bother you too much, I've found putting the output in a front corner, first blowing across the front glass, usually works best.

 

As I understand it, the concentration of CO2 changes the color, not the pH. But, the CO2 will also effect the pH. So, by the time you have enough CO2 to make your drop checker green, your tank's pH will probably drop by about 1. This should happen regardless of where your pH starts.

I could be wrong but I thought drop checkers contained bromothymol blue which is a pH indicator.

 

I could be wrong but I thought drop checkers contained bromothymol blue which is a pH indicator.

Yeah, I don't know how they work, but they work in tanks with different pHs. If drop checkers were merely giving a pH reading, why do they work in tanks with different pHs?

Edit: Given my lack of knowledge, I did some google searching/reading. Apparently yes, drop checkers use the pH indicator bromothymol blue...but the pH of the aquarium water is not important. Essentially, the bromothymol blue in the drop checker's solution is reacting to the amount of CO2 in the air inside the drop checker. This works, because CO2 in a solution drives down pH. The solution has been calibrated so that when the tank's water has 30 ppm of CO2, the amount of CO2 that is off gassed into the air in the drop checker makes the drop checker turn green.

 

Ph of your water has no difference in the readings from one tank with one pH to another tank with a completely different pH. A pH reading for water acidity or alkalinity is a little different than a pH reading from a drop checker. That is because drop checkers use a calibrated solution with a known water chemistry (4dkh) which only has buffers that are carbonate based. They will display a pH drop from added carbonates (co2), which is a little different than a pH drop if you were to add acidic water to alkaline or vice versa. The only thing that makes a difference in your drop checker readings are the dkh of the drop checker solution. A proper solution has 4dkh. As for your co2 dispersion, I think the issue is lack of water flow/circulation. It seems like your tank is on the bigger end? If it is, you should add a wavemaker positioned right above the diffuser. Theres a few benefits to this, 1) the wavemaker will act as a sort of reactor, it will suck up the co2 bubbles, spin them, and spit them out allowing for better absorption and longer contact in the water column. 2) plants generally like gentle flow and in my experience do better with better water circulation. I had an issue with co2 dispersion on a 3 ft long tank that is very narrow, it's hard to get flow to the far side of the tank without 2 canisters on each end. I bought a wavemaker and had much better results. Alternatively you can try and position the diffuser right below your filter outflow instead. May I ask why you are trying to cut down on the current from the outflow? Low flow+co2 doesn't work as well. It's kind of wasting your co2 at that point.