Confusion about EI and other myths

[yme]

plants our fish ? Chose one.

I totally agree. I made a mistake and am fully responsible. lifestock is of course way more important.
Saying this... if one get's the advice to increase co2 levels... and increase even more if plans are still stunting... people will push things too hard and shrimps will die. I am sure that I am not the only one who made this mistake.
What I do realize now, is that with more surface agitation you can get away with more co2. (thumbs up for the vortech!!!)

I think it helps if you have multiple aquariums also.

I do not only think it, I know it It is pretty hard to do statistics on n=1

what is the limit for co2

I don't know, but in about 6 really amazing tanks I measured around 50 mg/l.

[ismenio]

Thanks Tom , sorry the second post but i didn´t see your answer when i have post.
Thanks to Yme.
If we can´t increase the co2 we must decrease the light since the problem in most cases is low co2 for the light we have.

Regards

[yme]

@ismenio:

indeed! and, although it is just my experience, I think that a good current and surface agitation is very, very important.
Just saying: increase your co2 level is just not enough, it is a bit more complicated.

greets,

yme

[Tom Barr]

Measuring O2 + CO2 at the same time and over the entire day cycle is not easy.............but.for light and nutrients?
They are extremely easy.

Makes a big difference.

Regards,
Tom Barr

[Tom Barr]

Sorry Tom but i don´t have understand one thing.
The nutrients N P K Fe and others not affect the fishs but the co2 can kill them, what is the limit for co2 ?
And if we can not increase more the co2 because the fish? Decrease the light ? Nothing more to do i think.

Regrads

YME suggested a range in the 50ppm or so.
I have gone to 80ppm for some tanks, others in the 40-60ppm range.
I have high current though and highly stocked fish tanks.

So the O2 is 7-10ppm as well.

I think each species will have a limit of O2/CO2 ratios, both mst be measured to test the limits of the species of fish in question.

Plecos, Discus etc are more sensitive, or highly active fish that are larger.
Tetras and the typical shrimp/fish we see in nice pretty aquascapes (top winning in ADA's contest say) are really bullet proof, easily handling 80ppm or more ppm.

It's rare to see anything but in such contest.

Regards,
Tom Barr

[srozell]

Twisted tips was all about Ca+ according to many.

Yet not one person has ever showed definitively "why". I've lowed Ca++ down to 5ppm or so, pretty low, no twisted tips............

I find this comment interesting, perhaps you can elaborate on it.

Testing calcium and finding levels at 5ppm, while low, would indicate to me that there is still calcium available to the plants. I don't know how much calcium has to be in the water or substrate to continue to support plant growth (especially not knowing what else was limited in the tank). Perhaps you can elaborate on this.

[Tom Barr]

I don't know, but in about 6 really amazing tanks I measured around 50 mg/l.

Most nicer tanks sit about here at 40-60ppm IME. My 180 is up to 70-80ppm during the day.
I know you are one of the few that have the CO2 meter though.

I installed 2 of them this weekend.
I had to rewire the coaxil redox cables to accept the 2 leads from the Oxyguard.
This way we can correlate, data log and control CO2 ppm via the controlled Redox function.

Not an easy fix.

But.....it allows me polenty of play time with these things and I made 4 different methods to confirm that the readings where indeed accurate:

Sealed chambers and allowing the gas to settle inside and partial pressure law.
25% CO2:N2 mix vs a 100% CO2 gas.
Ultra pure water and a known KH buffer and then pH/KH scaling.
Oxyguard's calibration method(which did not do well vs the other 3 methods listed above).

The client's tank was CO2 limited, and within a min I knew it was, even though the CO2 read 40ppm, it had not been calibrated for almost 2 years.
It read 40ppm when it was really under 20ppm. The new meter and the claibration slope fixed this right up.

So even for me, the $$$ spent, the time, CO2 is a mofro bugger.

It'll burn any and everyone.
If not today, just you wait.

[Tom Barr]

I find this comment interesting, perhaps you can elaborate on it.

Testing calcium and finding levels at 5ppm, while low, would indicate to me that there is still calcium available to the plants. I don't know how much calcium has to be in the water or substrate to continue to support plant growth (especially not knowing what else was limited in the tank). Perhaps you can elaborate on this.

Yes, it is low, but few folks have tap less than this and we add Ca from many other sources as well.
If you used ultra pure water, or all RO water etc, and plain sand, no ADA AS or garden soils etc, dolomite, onyx sand etc etc.....
Then you do not do many water changes........

Now you might end up with an issue.
I've seen some very supper low Ca++ water in natural system and saw no evidence of any Ca++ issues.

I think the point is that while possible in aquariums, it would be something that hobbyist would have to go out of their way really hard to do.
CO2, on the other hand,........ is bugger of 7 th degree.

You are correct, 5ppm is still not limiting, but there might be several uptake enzymatic mechanisms that require say 1 ppm, 3ppm and 5ppm, anything above 5 will not change the uptake demand.
This is true for K+, NO3 etc....... and it would not be unreasonable to assume the same is true for Ca++.

CO2 can be used to illustrate this issue as well, while in theory, 3 ppm is non limiting as logn as it is resupplied rapidly.........we know plants do not grow at non limiting levels till we hit about 40-50ppm for many species.
So concentration does indeed drive uptake.

I should have seen some limitation at 5ppm for the claims to be correct, I tried to go out of my way for Ca++, I've yet to be able to do it, even with soft Sierra snow melt water with low KH and GH(1 and 2 respectively)
So there's more that we really do not know here, but CO2 seems to be much more likely, not Ca++.

Most of the Ca++ evidence comes from terrestrial plants, which we know are not CO2 limited like aquatics and the measurement and mainteance of CO2 is far easier.
So that reference for Ca++ is a poor comparison.

[yme]

hi!

Oxyguard's calibration method(which did not do well vs the other 3 methods listed above).

this concerns me!!

What would you advice me to do?
I calibrate once every 2-3 months or so. I find never a big difference between before and after calibration. 5 ppm at most.


I don't have N2 at home, so this method is not an option.

The pH/KH scaling seems most feasible to me.
However, how can I do this in practice?
Making the KH-solution is of course no problem.
But how can I add CO2 , mix it using a stirring bar and measure both CO2 and pH at the same time? (and don't make errors due to the slow respond time of the CO2-probe)
I don't really see yet the setup of this method.

thanks!

yme

[Tom Barr]

hi!



this concerns me!!

What would you advice me to do?
I calibrate once every 2-3 months or so. I find never a big difference between before and after calibration. 5 ppm at most.


I don't have N2 at home, so this method is not an option.

The pH/KH scaling seems most feasible to me.
However, how can I do this in practice?
Making the KH-solution is of course no problem.
But how can I add CO2 , mix it using a stirring bar and measure both CO2 and pH at the same time? (and don't make errors due to the slow respond time of the CO2-probe)
I don't really see yet the setup of this method.

thanks!

yme

Well, after looking at it, they also have issues with this also.
It's not easy for them to offer a user freindly method.

So I understand.

I tried 3 different methods to verify, not satifisied with their method for calibration myself.

If you can construct a nice large drop checker and can withdraw a smaple with a suction bulb, and have areference KH solution and a pH probe calibrated well in this water, and sealed, you can allow for a long time to pass and equilibrate.
Unlike a drop checker 2 huge trade offs, the time delay and the poor accuracy of pH, this is over come.

The reference solution is all pure water and sodium carbonate reference solution.

Since time in not really important for calibration, this can be allowed to equilibrate for 24-48 hours etc.
Then take a highly accurate pH reading.

This reading can then be used to adjust the slope of the CO2 meter.
You may/should also vary the CO2 content for the sample test water.
So try to test a low(no CO2 added), then med, say 30ppm and then say 60ppm.

Compare this reading to the tank's pH and KH reading, see if they match.
If so, you have few interefearing KH factors and can use the pH/KH relationship.
That was the case here, since they change water very often and use RO/blended with a little tap.

You can make these chambers out of acrylic, then add a rubber grommett for the pH and then another for the CO2 probe.
I think it would be even better to allow plenty of time, but add CO2 gas to the air in the dry part of the chamber to change the concentration vs the way I did it, which was a PITA.

Still, with a known KH and a pH meter, we should if the water is oure and only HCO3..be able to dial in a reference CO2 ppm to 1ppm or less perhaps.

There's another company that makes CO2 systems for ultra pure water, they go to the ppb range they say, seeign their claibration methods might be interesting, still, I like the IR for gas, then convert that from the seal chambers to ppm for aquaous solutions for the gas in the head space.