How does Plant Biomass affect EI Dosing

Discussion in 'Aquarium Fert Dosing' started by Hoejay, 24 Jan 2008.

  1. Hoejay

    Hoejay Member


    My thoughts are that plant biomass will be affected by

    Plant species - fast / slow growing , high / low uptake of Co2 , NPK Fe

    Leaf structure - broad leaf - fine leaf, total Surface area of foliage- cell structures ability to take up CO2 / carbon and nutrients

    Root system - established, surface area

    Is there any guide line as to how to assess or is it trial & error?

    If the Plant biomass is too low or the uptake of nutrients reduced by low CO2 and or light conditions then EI dosing will result in a max of twice the target weekly dosing level when equilibrium is reached. Is this a sufficient excess to cause algae problems?

    If this is the case would it be best to start EI with the dosing levels to reach the maximum weekly level at equilibrium and not at week one (i.e. assume 50% residual with a 50% water change, no uptake) and then adjust up when deficiencies are identified?


  2. Dan Crawford

    Dan Crawford Founder Staff Member

    Daventry, Northants
    You've got it mate, if there is not sufficient biomass then the excess nutrients are just left for the algae. i'd start off a new tank with half EI and 50% water changes and like you said try and judge for deficiencies etc by noting the effects on the plants.
    There are no set rules for EI IMO, the only rule that i stick to is to dose in excess. If you had a tank with hundreds of fast growing stems then maybe you would need to up the dosing where as if you had a just a carpet of HC then maybe you would need to lower your dosing, i really think it is up the the eye of the aquarist. Nutricalc for instance works well but deffinatly doesn't take into account each tanks differing biomass.
  3. GreenNeedle

    GreenNeedle Member

    Lincoln UK
    Also to take into account is that some plants use differnt ratios of each nutrient!.

    At the end of the day it is my understanding that the quantities in EI are calculated so that even if there were almost zero uptake, the reset each week stops it from getting to dangerous levels (which at the quantities dosed on EI would still be months to accumulate)

    As far as I know this is the reason for the reset and not algae as Tom says that excess nutrient does not cause algae if the plants are growing!!.

  4. ceg4048

    ceg4048 Expert/Global Moderator Staff Member

    Chicago, USA
    Hi Neil,
    Here is yet another perspective: Firstly, the primary EI mantra is that nutrients don't cause algae. If you believe that, then you have to believe that excess nutrients don't cause algae either. Part of the problem on a newly set up tank is that we typically put in plants that were grown emersed. This means that they are not yet efficient in water column feeding until they shed their terrestrial leaves and grow their aquatic leaves. Healthy leaves uptake nutrients and they also uptake ammonia. Since ammonia is prevalent in any new tank for weeks on end, this ammonia combined with the high light typically seen in high tech tanks causes algae.

    Water changes in EI tanks have less to do with eliminating nutrient buildup than they do with eliminating ammonia buildup. The decomposing detritus, fish and other organic waste, leaf remnants and the nitrogen cycle itself as well as soil leachate all contribute to ammonia buildup and are all curtailed by water changes.

    If all we were concerned about was nutrient buildup we wouldn't need to do a water change, we could simply stop dosing until the excess nutrients were consumed. :idea:

    The EI dosing concentrations assume maximum light, maximum growth rate and maximum nutrient uptake so that you avoid deficiency(which causes algae). Cutting your initial dosing by 50% is fine because you probably have less than maximum light, uptake is well below maximum and the plants are still very inefficient at uptake (during this time the plants can also use the nutrient reserves they built up while growing emersed.) But none of that can prevent algae. Ammonia spikes combined with high light will generate algae equally well whether you are dosing 100%, 50% or 0% of EI.

    The importance of high biomass during a tank startup therefore is that a higher number of plants can uptake more ammonia. A higher number of fast growing plants uptake ammonia faster. The less biomass in the tank the more important water changes are to remove the ammonia.

    There are more than one ways to skin the cat. The lean way works well, especially if you have an enriched substrate, but to a very limited extent, Barr's data shows that higher nutrient concentrations actually increases uptake. I interpret this to mean that the more quickly the plants start uptaking, the more quickly they will transition to the submersed form and grow.

    Hope this helps,

  5. nry

    nry Member

    Cumbria, UK
    I've cut my low biomass tank (2wpg, CO2) down to half-EI, I was getting mass hair algae after 8 weeks of setup, seems to have reduced the algae noticeably (not growing back much now every time I rip it out). Perchance the tank maturity has helped too, but I don't see the need to dose full EI for a low biomass tank, I think George Farmer did the same with the recent PFK tank (was it Jeff's Iwagumi?) for similar reasons.
  6. Ed Seeley

    Ed Seeley Member

    It was Jeremy's Iwagima - definitely not Jeff's! :lol:

    I have to say that while Tom Barr has done excellent research on the use of mineral nutrient fertilisers in planted tanks and found results that support his hypotheses; I can't help feeling something's missing here. I have initiated EI in a couple of tanks and both times have found algae started to grow rapidly, mainly diatomaceous or thread algae. And it seems I'm not the only one...

    I am not saying EI dosing causes algae, as I don't think it does, but why does starting it up sometimes cause problems? If ammonia is the cause of the algae, does adding nitrate stop the plants taking up ammonia? (I have read that plants preferentially took up ammonia rather than nitrate.) Or, as I suspect, is the change itself enough to cause problems? If so, what is the mechanism behind this? I think these answers might give us more clue as to the effective ways to maintain our tanks as no method works for everybody!
  7. ceg4048

    ceg4048 Expert/Global Moderator Staff Member

    Chicago, USA
    I agree that it could be pointless to dose full EI in a low biomass tank, but again, that has to do with the matter of not being anywhere near the maximum uptake rates. It's hard to make assumptions about any tank from a distance, but in many cases during an EI startup nutrients get blamed due to circumstantial evidence. CO2 distribution could easily be a culprit. Once the algae is induced, of course it will feed on whatever nutrients are in the water. If you then cut the nutrient dosing by half the algae strands will clearly not grow as quickly. It's easy to then conclude that the nutrient concentration was a factor, but the algae had already bloomed. Had the ammonia levels been controlled the bloom would not have occurred.

    Armed with only my belief, I've done just the opposite. I started my tank with double the EI dosing. The hair algae that I did get was directly attributable to poor CO2. An overlooked dilemma is the fact that we often put fish in our tanks early on, which limits the level of CO2 that we can achieve. This tank went fishless for months while I blasted it with CO2. I discovered that the optimum CO2 in this particular case was at a level which was toxic to fish. The only solution then is to restrict the light in order to reduce the CO2 demand. Additionally, 70-80% water changes were performed 2 times a week, while re-dosing at double levels after each water change.

    NH4 is a less energy consuming source of nitrogen. Stripping the N is easy, however high NH4 levels in the plant tissues is toxic. NO3 is a much more expensive N source. Inside the plant NO3 is converted to NH4. So although it's easier to use NH4, it's much easier to store NO3 for later conversion. When both NH4 and NO3 are in the water NH4 is preferred when it's concentration is between 0.5ppm to 2ppm. At NH4 concentrations of less than 0.5ppm NO3 is preferred but both are taken up. Since the NH4 concentrations in our tanks are well below 0.5ppm NO3 will always be taken up first and then NH4. Because the uptake rate of NH4 is lowered for each plant at our concentration levels, a high number of plants are required to collectively remove the NH4 which is constantly being produced in the tank.

    I've now cut back my tank dosage to normal EI levels, but not because of algae, but because of absurdly high growth rates. The only things we can do to combat the algae if we have a self imposed CO2 limitation is to do more frequent and/or larger water changes, add more filtration and flow and of course, lower the light. We can also add organic nitrogen removers like Purigen and zeolite in the filter beds. Also regular addition of the liquid carbon products like Excel and Easycarbo can help make up for the CO2 limits.

  8. Hoejay

    Hoejay Member

    Thanks for the responses,

    CEG could you clarify what you see as beeing unstable CO2. You state that you ran the tank at very high CO2 without fish. Presumably when returning to lower levels of CO2 for the the introduction of fish the plants did not show signs of changes in CO2 levels?
    Does this mean that there is a threshold for CO2 levels where stability becomes a problem?

    I am just starting up a Jewel Record 96 (about 80ltrs). I've got JBL aquabasis Plus topped with silica grit for the substrate. I plan to dose EI and use pressurised CO2. I've added 2x 24w T5 lights to the standard fit 20w T8 in the hood.

  9. JamesC

    JamesC Member

    Bexley, Kent
    Just like to add a few thoughts of my own. IMO Estimative Index is highly dependant on high and stable levels of CO2, which if not provided can start to cause problems especially if ammonia is present in the smallest of concentrations. As long as CO2 is good and ammonia isn't present EI works extremely well. It was desiged with a high light level and heavily stocked tank in mind. If your lighting or plant density is lower then you'll need to adjust accordingly. Also a tank full of fast growing stems with consume more nutrients than a tank full of slow growing plants. Best to start off with recommended levels first and then make adjustments slowly noting any changes. There are a few problems with some plants in soft water, but generally most plants love it.

    Reduce water column dosing right back with a lean dosing method and you get a bit more leeway with CO2 levels and also I think with ammonia spikes. This is what I've tended to see. Controlling plant growth with low levels of nutrients is the hard part, but limiting PO4 seems to work well. By limiting I don't mean removing, but supplying just enough for the plants to be happy. It does mean that that nutrients have to be added before lights on EVERY day though. This gives the plants PO4 in the morning but none later on in the day as it's all gone. That's the theory anyway. This brings it's own problem notably with GSA algae, but with a bit of tweaking it can be controlled quite well. Look at most low nutrient water dosing methods ie, Amano and you see GSA. I was pleasantly pleased to read one of Tom Barr's threads not long ago where he mentioned that plant growth can be controlled by limiting PO4. Then again it's nothing new and has been done for years with PMDD, often without people knowing they were actually doing it. Just enough PO4 was added from fish food on a daily basis.

    A big reason why a lot of people get algae problems at startup is that they don't plant anywhere near enough plants. This is IMO such an important thing to do. Just look at when George Farmer sets up a new tank, it is full of plants and very few algae problems.

  10. Dave Spencer

    Dave Spencer Member

    N. Wales
    Amen to that, James. I wonder how many tanks I have seen being started up on TFF, and thought they were doomed to failure due to the lack of fast growing plant mass.

    My Juwel Lido was my first ever tank, and I filled it out with fast growing stems. One year down the line, I find I can take quite a few liberties and get away without inducing algae.

    I did get BBA and blackbrush when the CO2 ran out without me noticing, but it was easy to get rid of, as was Spirogyra, when I failed to carry out the necessary water changes after a major substrate disturbance.

    This tank is now my N. Wales Mountain scape, with a fraction of the plant mass, yet it remains algae free. That`s not to say that I am not easing the lighting back until the plants really start to flourish.

    I didn`t follow this ethos on my next two tanks, and have paid the price for it. The 60cm Iwagumi insists on breaking out in Spirogyra once in a while, something that was easily cured in the Lido.

    A few months of 75% substrate coverage with fast growing stems yields a very stable, algae hostile environment in my experience. I don`t know what the mechanism for this is, but algae doesn`t seem to like a nutrient rich environment where there is a high rate of uptake of the nutrients by plants. Even excess nutrients seem to be unavailable to algae.

  11. ceg4048

    ceg4048 Expert/Global Moderator Staff Member

    Chicago, USA
    I like the plan on that Jewel. Yes, if you run fishless you can really go to town with CO2 - no limits whatsoever. Set you timers and open that needle valve throttle. It's like driving on the Autobahn. Exhilarating. 8)
    The minute you put fish in though you have to tiptoe round the tulips.:(

    Fundamentally, stability means the CO2 levels should not fluctuate over the period that the lights are on. It sounds obvious but it's actually easier said than done. :wideyed:

    If I could show a graph with "time" shown along the horizontal axis and "concentration" on the vertical axis, then, at lights on, -time=0- ppm should equal 30. Ideally, the graph is flat at 30 all the way across. In order for ppm to be 30 at "lights on" though the gas has to be running before lights on - maybe an hour or more. Barr's idea of an efficient injection system is one in which it takes no more than 1 hour during lights off for the CO2 concentration to rise to 30ppm. There are two practical problems here though>

    1. You can't really measure the CO2 accurately. Due to dropchecker response lag you only ever know what the ppm was 2-3 hours ago.

    2. If your injection is not efficient then the injection rate required to drive the ppm up to the target level in one hour will be higher than it should be. That often means that the max ppm level will be higher than 30 a few hours later, so you risk getting into the toxicity zone. The only way to adjust for that is to back off the bubble rate and turn the gas on more than an hour before lights on. This problem might be an overstatement for small tanks, but as tank size increases the inertia of getting that much water saturated becomes a pain. The problem is mitigated somewhat if the tank is covered because the water will hold a significant amount of CO2 overnight.

    Setting the proper Injection, or bubble rate, is not that easy because the plants are consuming the CO2 which would make that flat line dip as maximum uptake approaches.

    If you inject at a rate which gives you higher than the nominal 30ppm, depending on your fish it may still be OK and that means you can shut the gas off a few hours before lights off. There is a certain point during the photoperiod where consumption starts to decrease so turning off the gas early is one of the good things.

    So these are the adjustments I had to make when I added the fish. Essentially, I had to get my CO2 timing right by turning on the gas close to two hours before the start of the photoperiod and turning it off 4 hours or so before the end of the photoperiod. The more the plants grew the more CO2 they consumed and the more I had to inch up the injection rate. Also, I time the lights so that only 30% of the light comes on for the first hour or so, which give a bit more wiggle room.

    I agree with James about putting in lots of stems in the beginning, even if your scaping plan doesn't include stems. You can always rip them out later, but they are important because they grow rapidly and they get your "ecology" going more quickly. I'm sort of a stem freak anyway so I always follow the guideline as stated by James. The point that I try to get across is that nutrients in a tank are only capable of exacerbating an algae bloom. They cannot cause it. Regardless of the dosing regimen you use, whether it be PPS, EI, or PMDD you'll get algae if there is a threshold level of ammonia is present. This level is much lower than can be read on your ammonia test kit by the way. Algae in an EI tank looks more abominable because there are more nutrients for the algae to feed on once it gets started. Algae are opportunists so once spore becomes strand they feed on whatever is available.

    Dave, I've read a Barr theory that algae, over millions of years, have "figured" out that when the waters are nutrient rich, inevitably, higher plants would take over. Their niche is actually low nutrient water where there is little chance of higher plant invasion. The theory goes that this is why PO4/NO3 are not algae triggers. Ammonia on the other hand would signal decay and otherwise poor water conditions so this became a trigger for blooms. High nutrient uptake by higher order plants in a tank only means that those plants are healthy and are reducing the ammonia content via their own NH4 uptake mechanism, thus suppressing the algae trigger. If the tank is well established this also means that there is a healthy nitrifying bacteria colony present also consuming ammonia and further suppressing the trigger. When something dies or if a plant becomes unhealthy or if we disturb the substrate, or if we have poor filter maintenance, an ammonia spike is dumped into the water column. If high light is present the algae take immediate advantage.

    As far as I can tell, algae can't sense what other plants are uptaking in the tank. They don't care. The spores only look for their trigger. Each species has it's own unique set of triggers but I'm pretty sure ammonia is always in that set. :rolleyes:

  12. Sumo

    Sumo Newly Registered

    Rocha. Uruguay.
    As should initiate a tank with EI?

    CO2 30ppm
    Substrate: Clay, humus, sand.
    Full Planted.

  13. ceg4048

    ceg4048 Expert/Global Moderator Staff Member

    Chicago, USA
    Hola Sumo, bienvenudo! Wow someone in Uraguay read my post. :wideyed: I don't recognize the city name Rocha. Is that near to Montevideo?

    EI on an 70lts would go as follows:
    3X per week (tres veces por semana) 1/4 teaspoon KNO3 (potasio nitrato)
    3X per week 1/16 teaspoon KH2PO4 (fosfato monopotásico)
    3X per week 1/2 teaspoon MgSO4 (magnesio sulfato)
    2X per week 1/16 teaspoon CSM+B or 4ml Tropica Plant Nutrition

    50% water change once per week. Dose immediately after the water change.

    I looked at your post "Plantado de Sumo" in the "Paisajismo" section of your forum "Uruguay en El Acuarista" so evidently you have access to these powders as you referenced them in your post. The composition is first class but I can tell you need to add much more CO2 because the stem plants in the back appear to be under severe stress.

    It is not necessary to add potasio sulfato if you already add the first two items. If you have very soft water in Rocha then you will need to add enough cloruro de calcio but I cannot say how much. In that post the tank appears to have enough calcio.

    Since these are such small quantities it would be better to prepare a mixture of 4 weeks dosing in 600ml of water and dose 50ml of the solution:

    [3 teaspoons KNO3 + 1 teaspoon KH2PO4 + 6 teaspoons MgSO4 + cloruro de calcio] in 600ml water.

    Do not mix the CSM+B in this solution. Dose it separately on alternate days.

    Saludos y un embraco,
  14. Sumo

    Sumo Newly Registered

    Rocha. Uruguay.
    Hola Ceg4048
    Thanks for the "bienvenida".
    My city is 210kms Montevideo, south-east of the country, bordering South with Brazil (130kms).
    I am reading UKAPS forum because I found an excellent site JamesC, and I am interested in his experiments with the Urea. UKAPS forum is very good, I read it every day.
    Thank you for your answer, but I want to know the technique to start a tank with EI, which is done in the first few weeks, changes of water, dosage, etc. ..
    In "Plantado de Sumo" I used DIY CO2, 4 bottles of 2.5 lts, but it was not good, now I have pressurized CO2.
    In my last tank (experimental) I used everything that I am going to use the new 70-lts. ... c.php?t=77
    To increase the Gh, I use mineral water (10%), it adds Ca 8ppm and Mg 3ppm.
    Again thanks.
    Sorry for my English, I use Google translator to read and write, and my wife help me. :rolleyes:
    Saludos. Un abrazo.
  15. plantbrain

    plantbrain Expert

    Keep in mind if you drop below 30-50% plant coverage, or have higher light, or higher fish to plant ratios, no filter, low current, these all will affect algae and plants.

    So while NO3 and PO4 might not cause algae in a planted tank, this assumes that the above are addressed well in your tank.
    If nothing is there(no plants), something else will surly grow if you add lots of light.

    The real issue is if there's an interaction between plants defining the system or algae.
    What causes one to dominate over the other?

    As far as EI, it's juts a simple method to use to see what non limiting nutrients are like for ANY light intensity.
    You are not to use it like a sledge hammer, rather, it's just a starting point.

    If you have less light, you can add less. Lots of discus that are well fed, cut by 1/2 the KNO3 etc.
    If you have high NO3 in the tap, do not add KNO3, switch to K2SO4 instead for the first 1/2 of the week etc.

    Common sense applies. I assume folks have that but often times I see the same baloney that happens in politics, occurring here in the hobby. They take one snippette and apply it as heir thesis for critique without reading everything: hyperbole. This occurs often with Diana Walstad's book comments on the web.

    And with this method as well as most other methods.

    A simple approach:
    Progressively add less for time blocks of 3 weeks before reducing the dose down.
    Watch plants, growth, health etc.

    Keep reducing it down till you see stress in plant growth/health etc, then bump back up to the next highest level(give your self some buffer there also!, you do not want to teeter on the edge). This will account for increases in plant biomass as you prune or not. Also, you need to be consisent more as you get leaner values.

    A good solution to deal with adding this leaner amount to the water column and not teetering on the edge is something I've said for many years: try a sediment nutrient source in conjunction. ADA aqua soil makes this easy and consistent(compared to clays/muds, spikes, soil etc).

    Then you have more wiggle room.

    So: nutrients both in the water column and the sediment, frequent water changes, good current and CO2, moderate to lower light intensity, maintain stable gardening/pruning.

    Tom Barr

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