Dosing Organic Carbon

[orchidsnfish]

I was reading the CO2 majic thread and wondered if you can dose organic carbon on a marine planted tank. I know with freshwater there are products like flourish excel but I'm not sure if they would benefit a marine tank at all. I know it wouldn't be near as effective as a CO2 injection but would be kind of cool to experiment with.

Please share your thoughts!

Angela

 

[Samala]

I would not use excel on a marine tank if it has any macroalgae you like or sensitive invertebrates (corals, snails your particularly love or are rare, etc). The pathway intermediates in excel should work as carbon sources to the marine plants but there is an effect with excel in freshwater tanks of being an algaecide in some cases. It would be great just to have another two or three or eight people try out CO2 dosing (or really heavy aeration) to see if it benefits plants/macro like I'm seeing or not. Its not an established thing.

>Sarah

 

[Plantbrain]

I believe that Excel can cause blockage and inhibition of the CO2 uptake mechanism in most algae, it does not destroy the alga directly. It does slow down the new growth and seems to have a stronger effect on the algae than the higher plants, now.......this might be advantageous if you have a seagrass tank and do not want macros or microalgae in the tank.

So........it does have some potential applications.

Samala, I have a good relationship with the folks at MBA, they use open water systems and the waters are very rich in CO2, NO3 etc fro, the bay there. I gave a seminar there a few weeks ago for the their aquarist and they got pretty excited.

Some folks have suggested adding things like oats, bread etc........to enhance growth of plants via carbons sources.

To be very clear, this is dramatically different than adding inorganic CO2.

Sometimes in very clean tanks, new tanks especially, you have carbon limitation, this is not CO2 limitation, this is the carbs like we and the bacteria eat to survive.

Bacteria need a form of a reduced carbon to make energy, these C's are the electron donors in metabloism. Well, then this means you also need an electron acceptor.

So adding reduced carbon requires 2 Oxygens for each Carbon produced.

So you drain the O2 levels if you add too much, the problem is that to have a significant impact in such a small tiny system as our tanks, you would need to drain the O2 down a considerable amount.

You'd be better off adding heavy current and aeration or if you want more CO2, well heck silly, then add more CO2 then!!!

Why beat around the bush and reduce the O2 and not have nearly as much control? Go directly to adding CO2, that's what the weeds want, not bread


Regards,

Tom Barr

http://reefcentral.com/agreement.php

 

[piercho]

People who add organic C (vodka, sugar, acetic acid) to a marine tank do it to fuel bacterial growth, not to fuel plant growth. The idea is to increase bacterial growth in the water column. These bacteria take up nutrients from the water column as they consume the organic C, serve as food for some invertebrates, and are exportable by skimming. I see little benefit to plants ââ"šÂ¬Ã¢â‚¬Å“ directly ââ"šÂ¬Ã¢â‚¬Å“ by adding organic C. I would use CO2 or increase tank aeration if you know that primary production is indeed C limited.

IME using acetic acid in limewater dosed to the tank, there seemed to be a link between using organic carbon and initiating a bloom of cyanobacteria on the sand substrate. IMO, in an oligotrophic system where much of the N regulation is occurring through bacterial action in the sand bed, addition of organic carbon can shift production to fixers. IMO, the fixers bloom over a sand substrate because of the available nutrients (PO4, Fe, etc) in the bed. I also believe that mats of cyanobacteria can force release of these nutrients from the sand bed by limiting oxygen penetration into the bed and lowering the pH in the sand bed. So, it could be a self-feeding cycle that will continue to fuel the bloom until the N ratio is rectified, the population of cyano consumers catches up with the cyano growth, or the nutrient source is depleted.

However, when I had the ATS running, I could manage an oligotrophic tank and still add up to 3 Tbls/day 5% acetic to a 100G system and not cause a cyano bloom in the tank. My rationalization for this is that a properly executed ATS will act as an N buffer and tend to regulate the C:N in a tank while promoting low overall nutrient levels and high O2 levels in the system. Of course, the appearence of cyano after some intitial attempts at dosing organic C may have been entirely coincidental, and my postulates linking cyano with acetic acid dosing are entirely wrong!!

Anyway, I would be cautious adding organic C to a marine aquarium, and I would not add it with the idea of improving plant growth. In fact, by fueling uptake of nutrients by bacteria, it may limit plant growth.

 

[Plantbrain]

<a href=showthread.php?s=&postid=7177654#post7177654 target=_blank>Originally posted</a> by piercho
People who add organic C (vodka, sugar, acetic acid) to a marine tank do it to fuel bacterial growth, not to fuel plant growth. The idea is to increase bacterial growth in the water column. These bacteria take up nutrients from the water column as they consume the organic C, serve as food for some invertebrates, and are exportable by skimming. I see little benefit to plants ââ"šÂ¬Ã¢â‚¬Å“ directly ââ"šÂ¬Ã¢â‚¬Å“ by adding organic C. I would use CO2 or increase tank aeration if you know that primary production is indeed C limited.

Yes, but you can culture plenty of bacteria in a filter or a DBS. The sticky polysac's they produce stick to detritus etc which provide packets of food for algae spores etc, the export of excess nutrients can be done a number of ways, I prefer plants, that is what I am interested in growing, not bacteria so much.

These same bacteria have to use O2 to oxidize the reduced Carbon. So there's that trade off.

IME using acetic acid in limewater dosed to the tank, there seemed to be a link between using organic carbon and initiating a bloom of cyanobacteria on the sand substrate. IMO, in an oligotrophic system where much of the N regulation is occurring through bacterial action in the sand bed, addition of organic carbon can shift production to fixers. IMO, the fixers bloom over a sand substrate because of the available nutrients (PO4, Fe, etc) in the bed. I also believe that mats of cyanobacteria can force release of these nutrients from the sand bed by limiting oxygen penetration into the bed and lowering the pH in the sand bed.

Naw, the plants/macros are Nitrogen limited, but not the Cyanos, they live on less and when things drop, they pop right up.

Nor is it a ratio, at least in our tanks, this is true for both Marine and FW systems and the species that pester us simply live on less NO3's than the Macros/plants.

So, it could be a self-feeding cycle that will continue to fuel the bloom until the N ratio is rectified, the population of cyano consumers catches up with the cyano growth, or the nutrient source is depleted.

Well, it's not anything to do with a ratio and having tested this a number of times, it's simpler than this, it's the low level of NO3 folks often keep.

Do not limit the plant growth with low NO3.

I can have a wide range of N ratios, very wide and never get cyanos nor other noxious microphyte algae.

You can test and prove this to your self.

I'm not saying that this is true in central oceanic gyres, but there are few plants/macros there and no one is adding ferts and controlling limiting nutrients there either.

However, when I had the ATS running, I could manage an oligotrophic tank and still add up to 3 Tbls/day 5% acetic to a 100G system and not cause a cyano bloom in the tank. My rationalization for this is that a properly executed ATS will act as an N buffer and tend to regulate the C:N in a tank while promoting low overall nutrient levels and high O2 levels in the system. Of course, the appearence of cyano after some intitial attempts at dosing organic C may have been entirely coincidental, and my postulates linking cyano with acetic acid dosing are entirely wrong!!

Anyway, I would be cautious adding organic C to a marine aquarium, and I would not add it with the idea of improving plant growth. In fact, by fueling uptake of nutrients by bacteria, it may limit plant growth.

True.

I think the next time you get cyano, try a 3 day blackout(they ship corals and weeds and fish 3 days in bags etc, no need to fear). Then add KNO3 before after cleaning the cyano off to about 5ppm and then thereafter.

You can see if the Cynao comes back.
Gebnerally it will not if you maintain some decent NO3 level.

I mean really, what do you think you are limiting by limiting both PO4 and NO3?

You only need to limit one if you believe in limiting nutrient theories(I don't).

Regards,
Tom Barr

http://reefcentral.com/agreement.php

 

[piercho]

Tom, thanks for your feedback. I may be at cross-purposes by cultivating both coral and plants. For now, because of the coral, I'm too superstitious to push a 5 PPM NO3 level. I do intend to do some trials with adding NO3, but it would be more in the 0.1 PPM range, at least to start with.

 

[orchidsnfish]

I need to read up on that coke bottle CO2 system. I would love to try it with my 60 cube. I have some really cool macros and would love to see what CO2 would do for them. Still trying to talk my fiance into building me a real CO2 system .

Thanks for the feedback. Looks like I'll leave the excel alone then.

Thanks'
Angela

 

[Plantbrain]

<a href=showthread.php?s=&postid=7181844#post7181844 target=_blank>Originally posted</a> by piercho
Tom, thanks for your feedback. I may be at cross-purposes by cultivating both coral and plants. For now, because of the coral, I'm too superstitious to push a 5 PPM NO3 level. I do intend to do some trials with adding NO3, but it would be more in the 0.1 PPM range, at least to start with.

Yes, there is a trade off there with different species and culturing in small glass boxes.

It's much easier to maintain 5-10ppm of NO3 than 0.5-10.0ppm NO3.

So for ease of use/culture, I like the weeds more. They are easier to trace causation.

You can add more NO3 without issue to most corals, but limit the PO4 instead, it's easier and low amounts don't cause algae blooms, unlike NO3.

What test kit do you possibly own that is even close to being accurate at 0.1ppm of NO3?

Even the best Lamotte kit is only 1-4ppm accuracy over a 0-15ppm range..........

In aquatic freshwater planted tanks, NO3 drop at rates due to plants around 2-4ppm a day.

A good marine planted tank will have perhaps 25-50% this amount. So 0.1ppm.......that's not even worth talking about, that would last for a blip.

also, the lower you get, the less bioavailable the NO3 often is, same for PO4, but most smaller noxious algae do have the ability and are well adapted at cleavage of the organic bound fractions, whereas the larger macrophytes tend to rely on inorganic labile forms of nutrients and require far more.

Test kits you folks use do not distingush between what types of N or P, they test total N and P mostly and have poor resolutions at lower levels.

I would strongly caution against reading into them too much without making a standard curve with 3 standard solutions when you test anything and want to be accurate.

Folks have been making these mistakes in the hobby for many years and the correlation to the problems is often very poor and sends folks on long protracted goose chases.

In science, we make standard curves and that's the way things are done, you have to test the test kit method. Otherwise who knows.........

I get even more suspicious when the leveles get down very low, the risk of bottoming out is very high and provides very little wiggle room.

Some folks can a balance the bioload with the nutrient needs at low levels, but in most cases, there's some good old luck involved to that balance.

I'd rather use the wider ranges that are non limiting and focus on one nutrient, say PO4.

You cannot co limit both NO3 and PO4 realitiscally(It does occur and shifts back in forth in some systems) in a tank, so just pick the least problematic(fish foods tend to be higher in N than P).


Regards,
Tom Barr

 

[piercho]

What test kit do you possibly own that is even close to being accurate at 0.1ppm of NO3?

I don't. I talked this out on the chemistry forum. I'll make a stock solution using KN03 at a known density. I know the volume of water in my system. Knowing those two things, I can add the volume of stock solution that will raise the level of NO3 in the system by 0.1 PPM.

I won't know the level of NO3 in my system (assuming it remains below the range of the hobby test kits). But I can add N03 daily to bump it up by a known increment each day. As long as uptake exceeds the amount added, I should never see the nitrate on a test kit.

 

[Samala]

I thought that's what you meant Howard. Its a good idea too.. though Tom will think we're being coy with the NO3. Its just going to take some time to get people to play with testable levels. Plus, you've got corals and such, so its a good approach IMO.

This is not unlike what we've suggested to do with Fe dosing afterall.

>Sarah

 

[Plantbrain]

<a href=showthread.php?s=&postid=7202868#post7202868 target=_blank>Originally posted</a> by Samala
I thought that's what you meant Howard. Its a good idea too.. though Tom will think we're being coy with the NO3. Its just going to take some time to get people to play with testable levels. Plus, you've got corals and such, so its a good approach IMO.

This is not unlike what we've suggested to do with Fe dosing afterall.

>Sarah

No, not coy, I've done similar things with NO3 and other nutruients, particular traces as test kit errors are very common and AA's are not an average test method here

It's a very reasonable approach.
Butn it does not suggest that is enough nor tells you what the ppm is in the tank, how long does 0.1ppm last in a tank?
Maybe 1-2 hours tops in fully planted tank.

So.....what about the rest of the day?
Better than nothing.

After bumping it up, you can hit a range, but this is a bad assumption to assume that that is static range.

The plant /macro biomass can double and the demand can double, likewise, the pruning can slow things down and you get an ebb flow in the nutrient levels.

I think most can eye ball and predict this after some experience though. Visual cues are important and better deteriminants, I use the test kits to go back and figure out what is going on after I get a peroid of good growth, rather than relying on them for a method.

I try and repeat the good growth peroid and then test with a specific purpose and item(good growth and say NO3 levels) I want to look at.

This is a much better approach than chasing problems.
I'd rather chase the good growth responses.
Then that will ultimately yield a better set of conditions for the macros.

I also check to see how far over the levels are needed before we have a crash for each nutrient or an undesirabel effect.

This lets you know how much wiggle room you have in the targeted ranges and means much less testing.

When doing this, you also become aware on individual nutrient concentration impacts on specific algae over a range, rather than just one end of the low spectrum.

It's not that tough to do and algae blooms are fairly easy to rectify in a marine planted tank vs a coral tank and much cheaper.
The marine plants bounce back much faster and so we have a better system to work with at looking at nutrients effects on noxious species of algae and macros/plants.

Regards,
Tom Barr