Yo-han;64304 said:
I measure KH, and it fluctuates insignificant during the week. Never tested it on different times of the day but I don't expect much change there either. Have two dropcheckers in there as well, for control.
And no, it is not 100% bicarbonate. My pH is 6.4, so that will give me about 50% bicarb and 50% carbonic acid if i'm right. (pKa1 = 6.352 at 25 °C)
I've used pure DI water made up with sodium carbonate and flushed a tank, then added CO2 and used the pH/KH........., I've also used known % CO2, N2 gas mixtures(5% and 95%) to answer this.
You mention your pH is 6.4, but you did not mention what the KH was measured at.
What good is that with the other?
The influence of PO4 as a buffer is overrated. I ones calulated that 1ppm PO4 raises KH with 0.015 degree at pH 7.0. Below 7 the influence only gets smaller. I have no NH4 and since using purigen, little tannins. So not much buffer except for carbonates. So quite sure about my CO2 for as far as I can be without using expensive tests.
Tap water also has other non carbonate alkalinity as well, you risk being over confident here. SeaChem makes several so called "buffers" and they can easily toss the chart off by huge factors with fairly small additions.
Some tap water has odd stuff they add or is naturall present that also tosses the charts off. I've measured this stuff when I've gone to give presentations. According to the chart and the Lamott Alk test and the calibrated pH test meter, he should have had 220 ppm of CO2, but there's no way the fish could survive, this was in Ohio.
My own tanks with sierra snow melt and granite water shed, about as good and close to rain water as most can hope for, has enough to mess with the reference standards.
I end up with about an error of 10ppm. not bad really, but the KH does move depending on the time of the year.
I do not test it a few times and think it's okay. A simple way is to take a small sample once every 2-4 weeks and then freeze them.
Say 20mls, does not need to be much.
Then you get a better idea.
There is a lot more you do not KNOW than you do here and it does matter if you rely on a specific ppm for CO2.
I do not rely on a specific ppm for CO2 myself.
I work at it backwards.
I get a system that is stable, then go about looking for possible reasons why.
Then I measure the CO2, and then question how much I can honestly say and know about it.
I do the same for lighting, for nutrients, water column or sediment or both.
Filters etc.
So things are bust, that's good to know as well.
Some and many remain inconclusive........
And that's where it's at today with why algae grows.........
So that's why I expect CO2 of little influence. Larger allelopathic chemicals that reduce algae as well. But just saying healthy plants are more resistant, can't be true either. Because why do algae grow on glass, wood and rocks only when plants are doing bad...
Well recruitment is a separate issue from a bloom/germination. I can germinate seeds, but whether they survive and root well depends on WHERE they start growing.
A leaf is not the best long term place to grow if I had to pick one.
The leaf that is healthy in terms of carbon status will have a thicker cuticle. Some species lack any cuticle, but these species can afford to drop leaves and handle pruning easily.
A thicker cuticle may slough off the upper outer layer as more is produced from below.
If something interupts this, say variation that distrupts carbon metabolism.........then production of cuticular waxes...........long highly reduced carbon chains basically.........the algae have a much better site for attachment.
Non live materials also will recruit differently based on what the surface is like, this is well known and researched.
This is for macrophytic seaweeds, but should apply equally well to microphyte freshwater algae.
http://books.google.com/books?hl=en...sczoBCU2oI6O9b7ceESBlMQFA#v=onepage&q&f=false
Just throwing in a new ball I thought of: sgars! Could it be the other way around? Not allelopathic chemicals from healthy plants that reduce algae, but an (lets call it) allelopathic chemical from unhealthy plants that induces algae. First thing on my mind, sugars, but if someone knows anopther good one, just name it.
Well healthy plants already leach about 10% of their photsynthate as it is.....but it's possible. Recruitment would eb the key to look at on a variety of media and live leaves.
Setting up controls for these test is often very hard. It's a big question that has long been asked in Florida lakes and rivers where the bulk of the FW research into periphyton is done.
They have wide range sof nutrients, and no algae and the same pattern with algae. So algae and nutrients are poorly correlated (R^2 is under 0.13) where plants are present.
Crismann did look at CO2 in a couple of lakes and felt he got somewhere.
Not sure if he pursued it further.
You'd need to measure the O2/CO2 data logging over a season or two, which would be hard. But possible.
Read some article about someone who tried to use sugar as carbon source for his plants, ended up with more algae then before. Off course, I don't know whether all other parameters where kept the same, but they use sugar to grow algae for biogas, so there could be a relation there as well.
That would be Roger Miller, I know him, we had that talk some 10-15 years ago. The idea was bacteria would metabolize the reduced carbon into CO2..........but...........at the expense of O2, so with say 5-7ppm of O2........you'd have to resupply this as fast is it is produced........otherwise is would create a strong O2 sink and consume a lot of O2 for only a little CO2 gain. Not a good idea, it's the same as adding more fish to add more CO2.
That too also induces algae if you keep progressively adding more and more fish and keep the other parameters similar.
Most of my own tanks run in the 40-50ppm range for CO2, and a couple at the 60-80ppm range without any issues to live stock and good breeding from shrimp and fish.
I do not attempt to adjust the CO2 to given ppm, but tailor each tank's need based on the plants and the fish. Whatever the CO2 is, it just is. Then once stabilized and doign well, then I take a sample and critically measure it or use a claibrated meter that I know is not influenced by any KH issues.
In theory, you could make one from the drop checker and use a pH meter to measure the pH change in that small volume, I have a dual chamber with 2 holed rubber stoppes and 1/2" hole for the pH probe for this purpose.
Using hoses I can withdraw a sample, then take my time and wait for the equilibrium to be reached. I can also withdraw a smaple from a very specific location in the aquarium without it degassing. It's a sort of PITA to use it, but it does give good results and it takes day for the ppm' to be read. I'm okay with that. Then I can compare that to the CO2 meter reading at that same time and location. The best I can hope for has been about 1-2ppm +/- in agreement.
I'm still quite fine with the original premise however: healthy plants = healthy fish and little algae.
Sometimes folks spend too much effort and time with the ppm's and not enough watching the tank carefully and responding.
You can be all techy and a lousy horticulturalist. Likewise, some of the betetr scapers I know are lousy techy, but good horticulturalist.
Very few are both.
This is a human issue more so.
Good questions, thank you.