CO2 Bomb killed some of my plants?

[arielelf]

I don't think it was the cold, I made sure to not direct the stream anywhere towards the plants, and the plant damage is all over the tank but concentraited on the floor, not where the co2 was directed. I think John is right, I had the lights off over night, so that was probably the culprit.

So if I leave the lights on all the time whie the co2 is in the plants will be ok?

Originally Posted by Johno2090

Co2 does kill plants as I've done it myself many times, you need to remember that when plants have no light for photosynthesis they are much like any oxygen breathing animal. I personally use co2 canisters as opposed to your dry ice as I turn it off an hour before night. If you had the ice still in the tank with the lights off there would have been lack of oxygen for respiration causing damage to the plants.

[freaky_tah]

While the plants will be using oxygen during cellular respiration, generally they produce way more than they consume. It's possible that a complete lack of oxygen can harm them, but I'd think there would still be some within the tank during the time you didn't have the lights on. How long did you bomb the tank?

On a side note, this sort of reminds me of threads I occasionally saw on a freshwater forum, where people would say the plants were killing their fish at night because they used up all the o2...which in that case there's definitely another issue!

[Ed]

Originally Posted by freaky_tah

While the plants will be using oxygen during cellular respiration, generally they produce way more than they consume. It's possible that a complete lack of oxygen can harm them, but I'd think there would still be some within the tank during the time you didn't have the lights on. How long did you bomb the tank?

On a side note, this sort of reminds me of threads I occasionally saw on a freshwater forum, where people would say the plants were killing their fish at night because they used up all the o2...which in that case there's definitely another issue!

One of the things that occurs particularly in soft water aquariums is that there can be huge swings in pH over the course of 24 hours as plants take up CO2 (shifting the equilibrium of carbonates in solution) and then releases it. This can shift pH values by a surprising large values.

With respect to the plants.. If there was damage more to the plants on the bottom of the enclosure, I would expect that with cold damage.. keep in mind that cold gases sink.... which would mean that the largest change in temperature is going to occur at the ground level....