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Thread: Non CO2 methods

  1. #1

    Non CO2 methods

    While much of the attention and aquascape seen on the web focuses on CO2 enrichment in their methods, Diana Walstad presents an excellent argument for the approach of a non CO2 enriched planted Aquarium. We should also extend this to include Excel and carbon enrichment liquids as well as acetate which allow some algae to exist without any light or CO2 and grow heterotrophically (like us). She discusses not needing test kits, water changes, pruning often, dosing, work that most aquarist do not care for.

    What? You mean no water changes? Yes, that's right.
    No testing? Yes, that's right, but you can if you wish.
    Not much pruning? Yes, that's right, the plants grow much slower.
    No dosing? Generally yes for many easy to care for pland species(I'll discuss this much more later), the fish waste represents the dosing and you feeding them daily adds the nutrients.

    So why don't more folks do it?
    I'm not sure, given the goals they say they want when setting up a planted tank.

    CO2 is a bit like a drug addiction that hobbyists get hooked on. That's fine, but this non CO2 approach will give an excuse to have another tank that needs less attention and is cheap.
    I suggest folks coming from either the non CO2 or the CO2 enrichment approaches to give the other method a try and see what benefits it has.
    CO2 and non CO2 tanks work for all the same reasons, but........
    They grow at different rates.

    Based off of my testing, I'd estimate close to 5 to 10 times slower than a CO2 enriched tank at 2-3 w/gal. This rate of growth is such that the fish waste alone is enough to supply the needs for the plants. If we added more light then the CO2 would start becoming a more limiting factor and allow algae to grow better (algae need higher light to grow well in non CO2 enriched systems whereas the plants are much more limited without CO2). A lower light level is required, generally about 1.5 to 2w/gal is good.

    We also need a balanced fish load and feeding routine since this is our main long term input of plant nutrients. Fish food varies in it's amount and ratio of nutrients. This is not an issue unless it becomes limiting. Very often since non CO2 tanks get neglected, they have trouble growing certain plants. If these nutrients are not allowed to bottom out(Say PO4 or NO3), then many of the species folks suggest cannot be kept, suddenly can be kept in non CO2 tanks but they simply grow slower.

    Rather than suggesting allelopathy, Fe algae limitation, or PO4 limitation, I will say none of this exist. Rather, non limiting nutrient levels for plants will provide better conditions.
    Same applies for CO2 enriched systems, they just grow faster, but in both examples, the algae are never limited, algae is indirect, poor plant growth typically leads to algae blooms, thus plants define the system, not nutrients. When plants do poorly, they no long define the system, and algae can grow.

    CO2 will limit plants much more than algae, the lower light(the only limiting factor for algae in planted tanks really) and high plant biomass density will provide a better place for the plants and a worse place for the algae. CO2 and non CO2 tanks work well and are algae free namely due to high plant biomass that is relatively healthy. This plant biomass removes NH4 from the fish waste rapidly. Over time, the plants, adpt well to low CO2 ppm concentration by producing more Rubsico and associated downstream enzymes to fix and make do with much less CO2 than a CO2 enriched system.

    As long as the CO2 is stable, things are fine.
    Large water changes tend to add a spike of CO2 and this can cause instability. Perhaps algae sense changes in CO2/low O2. Speculation certainly.

    We can add KNO3 and KH2PO4 and show that in a non CO2 tank, excess PO4, NO3 (and Fe) do not cause algae blooms. We can add NH4 and induce a bloom just like a CO2 enriched tank.
    We can also add Fe at high rates and also not get any algae. This assumption and knowledge frees us from limitation of nutrients which ultimately does more harm to the plants' health and well being, allowing a better environment for algae to grow.

    Doing water changes adds CO2 back to a CO2 limited tank.
    Plants and algae both can and do adapt to low CO2 environments and induce genes to make enzymes that concentrate CO2 around Rubisco, the CO2 fixing enzyme. When we add the CO2 at higher levels back, this causes the plants and algae to destroy the low CO2 enzymes and start growing without of them since they no longer need them to fix CO2 form the KH ( the -HCO3).
    Why keep all this machinery around if you no longer need it? Doing weekly water changes "fools" the plants and helps encourage algae more. Algae are faster to respond to low CO2 than plants.
    Once the plants do adapt, they can do well.

    Soil substrates are popular with non CO2 users and they work well but peter out after about 6-12 months. They help the plants get established initailly abnd supply nutrients that are other wise lacking in the beginning before many fish are added and the tank has had a chance to accumulate waste.

    I suggest onyx sand as it added Ca, Mg, and Fe, and I add mulm/detritus freshly from another established tank to add bacteria and cycle the tank immediately. I also add a form of organic material other than soil. The bacteria that break the waste down need a source of carbon as an electron donor besides the elements in the waste. Like us, they need their carbs as well. As these bacteria break the carbon and waste down, they consume O2.
    This lowers the redox values in the substrate freeing up Fe2+ and other nutrients.

    Add too much organic matter and O2 and you get O2 levels that are too low and cause issues for your tank. Soil also has NH4, this we know to cause algae in higher amounts and it does not take much! Ways around this: don;t use soil, it's messy and has NH4/urea. Boiling the soil for a few minutes will oxidize the NH4 to NO3. Allowing damp soil to be spread thinly outside for few weeks(3) will allow the NH4 to be converted into NO3 by bacteria.
    Peat moss, ground peat, works well also.

    The other options are add lots of mulm instead and leonardite.
    Leonardite is great, it last a very long time, adds a slow release form of carbon, matches the gravel's color, sinks easily poses no issues if you disturb and uproot plants.

    You should always add fresh mulm to any new tank. Add some form of carbon as well, pre soaked/boiled soil, pre soaked peat, leonardite.

    Since the plants are the same as they are in a CO2 enriched tank and we know the rates of uptake are there, we can scale down the rates for the non CO2 dosing routine.

    I removed all fish and critters from the test tanks, I dosed only with KNO3m, and other inorganic fertilizer so that I would see only plant uptake and inorganic ferts contributions to the plant's health.

    Going back and assuming 80-90% of the nutrients will come from the fish load, I added once a week KNO3/KH2PO4.

    While trace mixes can be added, I decided to use SeaChem Equlibrium instead.
    It has Fe and Mn as well as Ca/K/Mg/SO4.
    I will add about 1/4 teaspoon per 20 gal tank once every week or two.
    This greatly enhances the growth of the plants.
    I also will add about 1/8" and 1/32" teaspoon of KNO3 and KH2PO4 respectively once a week or two.

    The plants will respond very well to this routine. You can let the tank go for awhile and not dose to purge any excesses that might have built up over a month or two or you can test to see rather than do the water change.

    DW does not suggest dosing, but adding 2-3 things once a week or two, certainly is not that tough???? the plants do gain a lot and then you can grow most any plant in a non CO2 tank.
    From here if you want more growth, Excel is a good option. You can add about 2-3x as much ferts then.

    I think it's important to look at dosing and longer term systems from a management perspective. While this is a method to add just water column fertilizers to the inert sands, and to test whether algae are limited in these systems as well, adding nutrient rich sediments, soils, or ADA AS, etc, will enhance the stability over time, and work synergistically like the CO2 enrichment methods.
    Things are not moved around as much, nor grow as fast, so soils and nutrients are left alone for longer time frames.
    The plants have ample sources from both locations and each last longer and has a backup in both cases.

    For testing purposes, "either or" helps, but we should also test them together afterwards to see if the combination works well also. By using the water column alone, we know and can measure the ppm's easily, and we alos know that the ppm's are non limiting to all algae. This is different question than how best to add fertilizers over time to CO2/non CO2/Excel based systems. Having shown that there is no limiting factor for algae and that algae is not a function of nutrients in the water column alone, this frees us up and allows us to better focus on plant health and growth.

    Which is the focus of this hobby in the first place, not killing algae.
    This method allows folks to slow the growth and maintenance down a huge amount, no CO2 makes everything less $$$ and easier to deal with.

    Try it.

  2. #2

    Re: Non CO2 methods

    Ooooooo (rubbing palms together) can't wait, Tom!

    I thought somebody should post something with 40+ views


    ps already voted the 5star Excellent, is that blind faith or what

  3. #3

    Re: Non CO2 methods


    I'm gonna be getting a new 5-10G tank just for this...

  4. #4

    Re: Non CO2 methods

    Canít wait either.

  5. #5

    Re: Non CO2 methods

    Just set up my 20 gallon. Ready and waiting!!

  6. #6

    Re: Non CO2 methods

    Just set up my 75 gallon tank with 2x55 watt compact flourescents with reflectors(AH Supply). Is this too much light for a non co2 tank?

  7. #7

    Re: Non CO2 methods

    Tom, I am wanting to order fertilizer from the PMDD store. Can you give me a general idea of what quantity and type to order for a six month supply. I have a 75 gallon tank. This way when you give the paramaters for dosing non co2 tanks I am ready.

    thanks, Walt

  8. #8

    Re: Non CO2 methods

    Quote Originally Posted by Dolfan
    Just set up my 75 gallon tank with 2x55 watt compact flourescents with reflectors(AH Supply). Is this too much light for a non co2 tank?
    No, about right.
    Bend the reflectors outward or make sure themlight hits all the way front to back.

    Tom Barr

  9. #9

    Re: Non CO2 methods

    Thanks Tom, I actually had already removed the reflectors but I can reinstall them. You can count me in on the freshwater plantfest in Fl. I'm only a couple hours away. Don't forget my dosing question please.

    thanks, Walt

  10. #10

    Re: Non CO2 methods

    Quote Originally Posted by Dolfan
    Just set up my 75 gallon tank with 2x55 watt compact flourescents with reflectors(AH Supply). Is this too much light for a non co2 tank?
    Yes, this is about right.

    It should be noted that most of the issue is about CO2 and competition between plant species, ome plants, Say Erios are very porr competitors for CO2, or L pantanal, whereas Hydrilla, Egeria densa are extremely competitive and adaptable species, these can use HCO3 as well as free CO2[aq].
    They also have much lower light compensation points, o they can use all the CO2 up before the light is strong enough to activate CO2 uptake/demand in other species.

    A good paper is by Bowes, Haller and Van, 1976 on Submersed macrophytes.

    Excellent description of 4 species and their differences in terms of light, CO2, growth etc.
    Tropica has a good discussion with CO2 and Riccia and the trade offs and allocation with Light and CO2(high low combos of each.

    I'll post a similar chart with light, CO2 and nutrients all together.

    Tom Barr


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