CO2 Advice

  • #1
I have a 29 gallon planted tank but no iron rich substrate, but use seachem flourish ferts, and apI leaf zone plant food. I am running a Fluval 88g (which I will probably upgrade) and want to learn the essentials before upgrading. I have been running a bubble wand all day at the same time as the CO2 is being fed by a diffuser. I use crushed coral to add a pH buffer so it doesn't crash.

I just tonight started turning the bubble wand off because I think its flushing the co2 out of the water. I also got a drop checker (along with 4kdh solution) to test the co2.

How can I make sure that the right amount of co2 is going into the tank? Currently at 1bps+
How can I be sure of the accuracy of the drop checker if the dKH is different than my tank water?
How can I make sure the fish don't die from lack of oxygen during the day? (I have an HOB that breaks the water surface and have that plastic oxygenation thing in the output.)

I am going to get another timer so I can plug in the air pump to run the bubble wand at night.
The tank gets warm during the day from t5ho lights, but am looking to get a fan that will draw some of the heat away.

  • #2
Wish I could help but I've been running injected for about a month. Ill try.

Yes, you do not want to run an airstone or have too much surface agitation while co2 is on. Little agitation is fine, like slight ripples.

Drop checker is suppose to have a nice green color to achieve the target of 30ppm of co2. They are slow at registering changes I believe. It takes a few hours of inserting it into the tank for it to adjust.

Plants provide oxygen during the day.

Someone else with more experience should come along soon. If not I'll find someone.
  • #3
Good advice above.

The airline is gassing off your CO2. You want as little surface disturbance as possible.

The end result of photosynthesis is not only plant growth, but is also oxygen. Please will release oxygen in the form of tiny bubbles. It is known as pearling as plants can look like they have been coated in little pearls of oxygen.

By using the 4 dKH solution in the drop checker your pH should be green after a few hours. Yellow and there is too much carbon dioxide. Blue too little.

When your tank has 30 ppm CO2 its pH will drop 1 degree so long as your water is properly buffered. You need at least 4 degrees GH and KH to stabilize pH or it will crash.

You may also want to rethink your ferts. The more light over a tank the more important balanced ferts become.

Ideally parameters should be...

5-20 ppm NO3
4 dGH
4 dKH
0.1-0.5 ppm Fe
10-30 ppm K
0.5-2.0 ppm PO4
  • Thread Starter
  • #4
Ok, so being that I only have some of these test kits and have little control over how much Nitrate, and Phosphate are in the water... I need to dumb it down to what I can control.

I see that my normal stable ph of 7.2-7.4 has dropped to 6.6-6.8. I added a little bit more crushed coral for some buffer (and a slight ph rise) in the event the old coral was no longer providing it.I started turning off the co2 at night along with turning on the airline. I made sure to have little to no surface disturbance during the day and have the co2 on. I just started noticing air bubbles drifting off some of the plants. I just got a second 6700k bulb, so that makes 2x31 watts of 6700k. This should hopefully help the plants along. The drop checker is now lime green. Have never seen it get yellow, so looks like its in good shape.

Should this let me avoid testing for GH and KH since the tank has been stable by using crushed coral for almost a year now?
Does crushed coral get used up?
I just dose plant ferts during a water change, which I assume resets the amount of available K,PO4,Fe (liquid each change, tabs less often.) Can this be a dumb way of keeping these balanced?
  • #5
I know nothing about CO2 kits, but I do know that yes, coral does get used up and needs to be replaced.

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