Too much CO2?

my thoughts were that 1 plant in a low light tank won't really benefit from CO2 if it doesn't have the excess light, however with a number of plants in a low light tank, is it not possiblethat betwen them they could use up whatever Co2 is naturally available? or would they use that little in low light that even in a heavily planted low light tank they would not use it all up?
 
in addition tothe question of OD'ing on CO2, I have posted this in the freshwater forum:
in my 20XH tank I am running DIY CO2 along with a couple low light plants and 6-7 water sprite. I was told the CO2 probably wasn't necessary but couldn't hurt and i tw as almost impossible to overdose on it unless my fish were gasping at the surface.
SO.... I was watching the tank last night and the furcata rainbows and Endlers all seem to be swimming right at the surface, almost like skimming for food I was worried that I had hit the point where they were running out of O2. However the platies and the neon and cardinal tetras are all swimming mid level and don't seem to be having any issues. Thoughts? Suggestions? picking up a drop checker to monitor the CO2 levels but any help would be appreciated.

I thought I would pose part 2 of the question in here since plant people tend to have a better understanding of CO2 than "non plant" people. We will be away for a coupleof days over the holidays, and while I am not concerned about the fish since I know a day or 2 without feeding isn't something to worry about, with the lights being out for a few days and not a lot of ambient lighting, would I be better to unhook the CO2? ( I have one little canister that came with a kit and a 3l Juice bottle with jello/yeast)
 
I know my guppies would often stay at the surface at night, when the rest of my fish were at lower levels. Also CO2 will not remove O2 from the water, so even if your DIY CO2 generator was working at peak efficiency, it would not remove the O2 from the water. How big are your plants, and do you have any surface agitation? Any chance of a picture?
 
no pictures unfortunatly. No surface agitation since I minimized it so as not to lose CO2. Have 2 Vals ( sorry don't know the names) 6-7 water sprite and another low plant I picked up on the weekend, of the anubis(?) family I believe. listed as low liught and slow growing, mostly for ground cover. I know it doesn't displace CO2, and I reassured myself that the lack of surface agitation should be made up for by the plants producing O2 right? Just wasn't sure if I should unhook it for the couple of days the lights won't be on since I realize I am probably more overstocked than I should be (although the rainbows are all very young still and much smaller than they will eventually get.) My concern wasn't so much the CO2 displacing the O2 as it was worring that without the surface agitation that the water would get oxygenated enough to sustain the fish load
 
Too much surface agitation will drive off CO2 but no surface agitation or movement will not allow gas exchange for 02 to enter the tank. In a heavily planted tank O2 may not be a problem but it's still possible. You're looking for a balance where you aren't wasting excessive amounts of CO2 while also maintaining a proper 02 level throughout the day and night. Increase the surface movement so you have a gentle ripple but not to the point where the water splashes.
 
If the light isn't there, you shouldn't need CO2. The need for carbon in plants follows the need for light. Light would be your limiting factor depending on your photo period.

CO2 can still help. This tank has 1wpg T8, 30ppm CO2 mist. NPK + trace daily:
cryptsen2.jpg


Original post can be found here.
 
AquariaCentral.com