View Full Version : Tank With Just Plants - CO2 Rate?
Roan Art
03-09-2006, 12:23 PM
ATM I have all my high light PNG plants in my last 75g. No fishes or anything. The tank is at 3.5wpg.
How high can I run the CO2? At what level does it cease to be beneficial to the plants?
Roan
beviking
03-09-2006, 1:18 PM
:huh: Is there a limit? IDK?
doesn't Barr's report say that 30- 35 ppm is the max uptake?
or is that the max that it's safe for fish - i'll have to go back and check. . .
cheers-Kyle
Slappy*McFish
03-09-2006, 1:23 PM
Yeah, good question. I'd like to know, as well.
EcoPit
03-09-2006, 1:33 PM
doesn't Barr's report say that 30- 35 ppm is the max uptake?
or is that the max that it's safe for fish - i'll have to go back and check. . .
cheers-Kyle
I read it yesterday, and I am pretty certain that he said that was the max uptake of the plants. I am pretty sure it was in his article on the Estimative Index (the link for which I got from one of your posts RA).
EcoPit
03-09-2006, 1:43 PM
Research on three aquatic weeds showed that the plants will reach and carbon fixing maximum at around 30ppm of CO2 no matter what light intensity is used (Van et al 1976)
Found it.
Roan Art
03-09-2006, 4:02 PM
Huh. You sure? Just wanna make sure cause 1976 was a LONG time ago.
FWIW I had that puppy screaming at 366+ ppm yesterday HAHAHAHHAHA
pH was probably lower than 6.0 -- that's as far as the kit reads -- and the KH was at 13 KH.
Heh. Just hadda do it :devil:
You just hadda see the Myriophyllum tuberculatum and the Pogostemon Stellatus. If plants could smile those guys would put a tradiional happy face to shame.
Roan
wow i totally missed the date on that report! 1976! should i relly be using his theory for fert dosing then?!
Roan Art
03-09-2006, 5:13 PM
wow i totally missed the date on that report! 1976! should i relly be using his theory for fert dosing then?!
Probably fine, but we wait for RTR or Tom or djlen to pop in and tell us we're dorks :)
I'm gonna snap a pic this eve. You guys have just GOT to see these plants. They've been in the tank for three days and are growing already.
Roan
reiverix
03-09-2006, 5:35 PM
I've also read that around 30ppm is the max uptake. If I crank my CO2 I do get more pearling but can't really say if I get more growth.
can't wait to see those pics!
I don't know what the max uptake is. My understanding is that the 30-35 ppm is the max for fish/shrimp/etc. - and some sensitives will be a bit lethargic at that, but do adapt.
There is mucho debate but precious little data going on right now about measuring CO2. APD, APC, and I assume the other plant tank areas are running a bit warm on the topic.
Roan Art
03-09-2006, 6:05 PM
I don't know what the max uptake is. My understanding is that the 30-35 ppm is the max for fish/shrimp/etc. - and some sensitives will be a bit lethargic at that, but do adapt.That's what my understanding was, too, but couldn't remember where I read it.
There is mucho debate but precious little data going on right now about measuring CO2. APD, APC, and I assume the other plant tank areas are running a bit warm on the topic.
Hrm hrm. Well, at some point the water has to become overstaturated with CO2 to the point where it can't hold anymore, no?
I'll check around and see what I can come up with. I'm pretty sure that 366 ppm is a wee tad more than the plants can use :D
Roan
sh!t, you think?!
HA HA :)
Captain Hook
03-09-2006, 7:48 PM
I'm running my tank at around 45 ppm daytime levels right now. The fish and shrimp seem fine.
I've read of people on various boards having their CO2 at high levels. Sometimes near or above 100 ppm if I remember right. I'm not sure how high the CO2 has to be before it stops making a difference though.
Aren't you going to go through your CO2 pretty quick at 350+ ppm? :D
Roan Art
03-09-2006, 9:45 PM
Got pics?
Myriophyllum tuberculatum
http://members.cox.net/rainbowfishes/images/tuberculatum%201.jpg
http://members.cox.net/rainbowfishes/images/tuberculatum%203.jpg
Broader pic:
http://members.cox.net/rainbowfishes/images/tuberculatum%202.jpg
Far left, front: Pogostemon stellatus (pinkish color), tuberculatum, vallisneria caulescens
Back: Limnophila sesiliflora, Rotalla wallichii (hard to see), vallisneria natans
Also in this tank: Blyxa Aubertii, Blyxa japonica
Remember, this isn't a "planted tank" it's just holding my plants until they get acclimated to my water. I will be transplanting most of them out over the course of the next few weeks.
Yes, the bubbles are CO2 :D
Roan
Roan Art
03-09-2006, 9:47 PM
sh!t, you think?!
HA HA :)
Away wi' yah! ;)
Roan
Roan Art
03-09-2006, 9:51 PM
I'm running my tank at around 45 ppm daytime levels right now. The fish and shrimp seem fine.
I've read of people on various boards having their CO2 at high levels. Sometimes near or above 100 ppm if I remember right. I'm not sure how high the CO2 has to be before it stops making a difference though.
Aren't you going to go through your CO2 pretty quick at 350+ ppm? :D
Away wi' yah, too! ;)
I turned it down, of course. I just wanted the fun and luxury of cranking it up and being able to say, "Yah, I tried that". :D
I read that:
1) some people have such high phosphates(?) in their tap that even at 100 ppm, they really aren't as high as their calculations say they are.
2) or their water for some reason doesn't "hold" the CO2 and they are pumping it in and right out.
I think ONE of those two is right, not sure which. Or perhaps a combination of the two. Hope someone can clarify.
Roan
That us in fact what the cuttent debate is about. The grids for pH/KH/CO2 assume that all alkalinity is bicarbonate and that there are no, repeat no, organic acids in the water. In some natural waters, at least the first of those conditions apply, in some the second may apply. With municipal water system water and established tanks with fish, plants, and with myriad supplements, it would be the rare case for both to apply, but frequently the two are not far enough off to make the grid worthless. Unfortunately, for many folks' tanks, the grid is a dream, giving a meaningless numbers.
At the moment, perhaps the most realistic reading is be taking the pH of the tank, collecting a sample of the water and allowing it to age 24 hours and then checking that sample pH. If there is a log difference (one full pH step, say pH 7.0 in the tank, 8.0 in the 24 hour sample), then you had ~30 ppm CO2 in the tank at the measure the previous day.
This requires high accuracy from the tests, so a calibrated pH probe is about the only effective device for such tests.
Captain Hook
03-10-2006, 3:20 AM
Nice pics! Those plants have some awesome colours, hopefully they stay that way. Your Pogostemon stellatus (I think) has a beautiful light purple colour to it. The red in the Myriophyllum tuberculatum is also nice.
Here's a thread I've been reading on APC that has a couple people that mention they consistently keep their tanks at 170 and 200 ppm, with fish!
Discussion about a new way of measuring CO2 based on the pH's change from its starting point (http://www.aquaticplantcentral.com/forumapc/science-of-fertilizing/14281-another-co2-chart-to-try-2.html)
That is because they cannot measure the CO2 accurately, not that the dissolved CO2 is in fact at that level.
Back in my lab days, where we used used gases (CO2/O2/N2) to control culture pH and/or ORP, measuring CO2 accurately was a practical impossibilty. And we had full analyses of the culture media, so knew exactly what was in the vessels. If we could not do it will hundreds of thousands of dollars in instrumentation and the FDA looking over our shoulders, I don't see accurate CO2 determinations in the hobby world being a realistic expectation.
We are left with TLAR (that looks about right) and very rough estimates. This is not that bad a thing. Planted tanks are biologically and biochemically complex, but are not rocket science. Approximations and compensations are not only acceptable, they can be preferable in the real world.