I don't think plants uptake plays
any significant role here. I did some measurements and after the lights turn on, the CO2 concentration falls down
only by 1 mg/L !!! I don't understand this too well, but it seems that plants absorb only a
small fraction from our CO2 supply. This confirms Tom Barr also:
So the key to constant levels of CO2 is the
amount of degassing (= aeration or surface rippling). How long before lights we should begin to supply the CO2 depends on the
injection rate. You can look at my charts:
www.prirodni-akvarium.cz.
Every days a school day
, I didn't know that about the uptake rates of plants, but either way co2 needs dialling to each individual tank as you say off gassing effects concentrations and there are many variables which effect off gassing; surface vegetation, physical plant mass, tank covers, surface agitation, filter type, most likely even tank dimensions and surface area etc. This is why each tank needs dialling in carefully and there is no set rule. Injection rate naturally dictates when you begin the process, but it must be balanced with the depletion of co2 in whatever guise, some need slower but longer injection rates, others can use higher rates. I simply can't get a level of safe and constant co2 without using a slower injection rate set to begin several hours before the photoperiod. Most likely down to the rate of off gassing in my particular tank, but it doesn't seem to change irrelevant of surface agitation or not.....maybe then its down to O2 concentrations also and If I could increase this then I could achieve better co2 levels.
I've read recent posts from Tom about off gassing and O2 concentrations, he advocates wet and dry filters to increase O2, and although these off gas more they help stabilise co2 at high levels which is another consideration to the hobby. It seems in the UK that canister filters are the norm, many have great success with them, but Tom prefers wet and dry trickle filters for the reasons above. Tom has clearly done extensive tests and research, unachievable by many hobbyists....heck, I can't even a afford a decent accurate ph pen which would help confirm what was going on in my tank regards co2. I just need to see what is happening and do the best I can with what I have. I just try to keep it simple with low light, its easier that way
......although I do want to be able to run a high light set up eventually so I can practice trimming techniques
to quote a phrase my mam used to say, "there's only a couple of weeks between a good haircut and a bad one", in my tank that would be months, high light would speed things along so I could trim and retrim without having to look at my mistakes for too long.....but I digress
Basically for plantnoob, its important not to get hooked on bubbles per second, they are only a guide, bubble counters differ and tanks differ. The most important thing is achieving good levels of co2 which need tweaking either by duration or injection rate.
Cheerio,
Ady
. this is after 2 and a quarter hours , still too blue to my eyes .
