Freshwater Aquarium Plant Growth & Nutrient Deficiency Issue...

[LabTest57]

The plants I have are: Amazon Swords, Aponogetons, Water Lillies, Riccia, Annachris, and stem plants with weird names ( I forgot how to pronounce or even spell them) though some start with "C".

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Okay, I've researched the factors that may be contributing to stunted growth and yellowing in the leaves. The factors that I tested out were: Iron, GH, salt, chlorides, light, KH, and PH.

The plants I have are either for hardwater or softwater environments. Testing both in a seperate aquarium proved to be useful, though the PH remained constant at ~7.0. In a hardwater environment with the GH being 400 ppm and above (sometimes around 600), all plants seemed to flourish, however, the softwater plants took longer to grow. *Note: I've been doing this experiment for about a year already as I have a lot of plants to do this. In a softwater environment with the GH at 80 ppm and below and KH at 70 ppm and below, the softwater plants seemed to grow quite faster, but the hardwater plants did not.

It seemed like for any plant that had yellowing in their leaves, I assumed it was CO2 and/or iron deficiency. Instead, I tried giving more wattage of light (don't feel like being specific) or more light for more hours (16 hours a day). After several months, there was still no difference. Right now, I have been using ferrous gluconate to keep my iron levels 0.1 ppm above the recommeneded for a week already, but still no improvement. Also, in the fish+plant tank, I always add API aquarium salt or table salt at 1 tablespoon per 8 to 10 gallons of water (table salt differs in composition to the API aquarium salt, so less should be added) every water change. I realized that most plants cannot tolerate even low levels of salt as well as high levels of chlorides in the water. However, these same type of plants were in a seperate tank for testing with no salt at all, and still they showed the same "yellowing" appearance.

I knew that a low PH with a reasonable KH would increase the CO2 in the water for the plants, but I would have to test these parameters daily. I kept the PH at 7.0 to 7.5 weekly (I changed the PH back to 7.0 every weekend). Now, it was the time to lower the PH down to 6.5 and have the KH at 40 to 90 ppm, and the GH at 100 to 150 to keep the water between soft and hard. Although I assumed that CO2 would be higher in the water, I knew that this wasn't the ideal PH for a community tank; however, in the literature, it states that a low PH allows plants to use up nutrients, minerals, and CO2 more efficiently, while a high PH may force the plants to convert carbonates/bicarbonates into a carbon source as food and cause calcium scaling or biogenic decalcification on the plants' leaves and/or stem. A plant that cannot utilize carbonate/bicarbonates as a carbon source in water with a high PH, or an environment not suitable for that type of plant can lead to detrimental effects.

As a result, the PH was the factor that determened whether my plants were able to utilize the ferrous iron and CO2 in the water efficiently or not. Although, this may have worked for me, there are many other factors that can lead to growth and appearance problems with freshwater plants.

[Tech Support AN]

That is very interesting LabTest57! Thank you for keeping us updated on your on-going research. We welcome any knowledge or feedback from your findings!

[LabTest57]

Can anyone confirm this: "Plants are able to store minerals, when there is very low levels of vital nutrients in the water."

Will my plants eventually show signs of chlorosis and/or necrosis, if I don't add any mineral or vitamin supplements for a month or two? Does it take that long for plants to use up all their stored minerals?

[Tech Support AN]

Thanks for the question! Plants will begin to store excess nutrients only when there is a high concentration and the plant has met the critical level needed for growth. If there is very low levels of vital nutrients, then the plant will not be able to store any excess, as they will be utilizing them for growth. I would not recommend going a month or two without supplementation of critical vitamins and minerals, as you will definitely begin to see slowed growth and other deficiencies such as necrosis and chlorosis. I hope this was helpful and please let us know if you need further assistance.

[LabTest57]

Okay, what if I add about 0.5 ppm of iron for only one week. Would any of my plants store some of the iron? If the iron in the water drops to 0 ppm for a whole month, would those plants still have some iron to use? How long are most plants able to store iron or any other nutrient?

[Tech Support LK]

Not really sure about that question. I would imagine that it would be different for each species. Additionally, the amount of iron stored in the plants will be dependent upon many variables and other parameters. I am sure there are some journals out there that have some conclusive answers to your question, but I am unable to provide you with a definite answer on this.

[LabTest57]

Instead of going to my local library, I found these relevant sites on the internet:

http://www.algone.com/planted_aquarium.php
http://www.algone.com/plants.php

A few excerpts from these sites:

Nitrogen, calcium, magnesium, sulfur, potassium and phosphorus (macronutrients) are needed in larger amounts. Iron, zinc, cobalt, manganese, and others are needed in smaller amounts (micronutrients). Macronutrients are usually in ample supply in the aquarium water, micronutrients have to be added from time to time, and are best placed into the substrate.

Nitrates should be kept at low levels, as excess nutrients will promote algae growth. Water changes of about 20% every other week will replenish the macronutrients. You should add macronutrients only if you have undetectable levels over an extended period of time. Most plants can store nutrients for later use. (aquatic plants)

Nitrogen, calcium, potassium, and phosphorus are in ample supply in the aquarium, and also sufficiently available in tap water.

Other nutrients and trace elements such as iron, zinc, copper, etc. are present in the substrate and need to be added from time to time to ensure proper plant growth.

It is well established, that plants are able to take up nutrients through their leaves and root system. The only nutrients necessary in the water are calcium, magnesium, potassium (limited), and carbon. The other essential nutrients should be in the substrate, as the substrate and the plants have the ability to store those nutrients for a period of time, making them available when needed. It is recommended to have phosphates available in the substrate vs. having it available in the water column, which allows algae to freely feed on them.

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Here's an excerpt from this site:
http://www.freshwateraquariumplants.com/nutrients.html

One of the myths destroyed by Sears and Conlin was that phosphorus in the aquarium should be entirely eliminated to avoid algae outbreaks. Phosphorus is needed by plants as one of the three Macros, the other two being Nitrates or Nitrogen and Potassium. The ratio that you are shooting for in a planted aquarium is roughly one part phosphorus to 10 parts nitrates to 20 parts potassium. While some have no detectable phosphorus when testing, plants that do not have access to phosphorus will not grow (Liebigs Law, if one nutrient is missing or deficient, plant growth will be poor, even if the other elements are abundant) and then algae has a chance to take over. On the other hand, some have excess amounts of phosphate, too much phosphate interferes with the metabolism of vital iron and disrupts the photosynthesis process, the result being poor plant growth.

Another excerpt form this other site: http://faq.thekrib.com/plant-qa.html

Plants can store some nutrients and trace elements, using them later. When they come from the greenhouse, they are fully stocked. But after a month or more, if you do not supply them with a balance of nutrients they take what's missing from their stock. When the stock's gone, the plant dies.
Most potted plants are grown emersed (hydroponically) in greenhouses, and are used to growing in very high light (i.e. filtered sunlight) and with high levels of nutrients, and must acclimate to aquarium conditions. First, they'll lose the old leaves which were growing out of the water and produce new leaves that have a different shape and firmness. Secondly, as they acclimate to the lower light and nutrient levels their growth rate will temporarily slow down.
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So, from the infromation on these sites, I'm better off buying Flourish Tabs or just Flourish (the comprehensive one). Also, it states that I cannot keep any plant for more than a month without the proper levels of micro and macro-nutrients; however, micro nutrients are needed more than macro nutrients (like a priority for which nutrient an aquatic plant utilizes the most, but both types are still needed to avoid any deficiencies). CO2 is dependent on the type of plant and how much light is available for the plant - with more light more CO2 will be needed for photosynthesis. Although my tank setup is different, in which I use less light but manually control the CO2 levels in the water, my plants still require a comprehensive amount or broad spectrum of nutrients (both micro and macro).


About Flourish Tabs, can I just put the tabs next to the plant, rather than in the gravel? I'm going to have a hard time getting the tabs into gravel, because my gravel consists of large rocks, pebbles,etc. and I'm not sure if the tabs will crumble into little pieces before I can get them at least 1 inch below.

I think Seachem Flourish is my best bet instead of the Flourish Tabs, however, why are the micro and macro-nutrients available at a way lower percentage than the ones in the "Parameter Specific" Flourish products? For example, how does 0.32% of iron in Seachem Flourish compare to 1% of iron in Flourish Iron ( 0.03 ppm vs 0.1 ppm)?

Does Excel work better in low-light environments, or high-light environments? How would you compare Excel to a DIY CO2 reactor, which at least adds some extra CO2 in the water column?

[Tech Support EH]

Many planted tanks thrive with only the addition of a broad spectrum supplement, such as Flourish or Flourish Tabs. However, in our experience, as tanks become more heavily-planted, one will begin to notice limiting factors of growth. Let's take potassium as an example. Potassium plays many roles in the cells of plants:
*Enzyme activation
-K activates at least 60 different enzymes in plant growth by altering the physical shape of the enzyme, therefore, the rate of enzymatic activity is limited by the rate at which K enters the plant cell
*Stomatal Activity
-K regulates the opening and closing of stomates, the pores through which leaves exchange CO2, water vapor, and oxygen
*Photosynthesis
*Transport of sugars
*Protein synthesis
*Starch synthesis

Therefore, oftentimes, adding a comprehensive supplement will not provide enough of the nutrient that is deficient; this is why Seachem has a different product for each of the micro and macro-nutrients. It is also important to keep in mind that different species of plants have different nutrient requirements.

Flourish Tabs are most effective when placed in the substrate and therefore near the root systems of the plants. When we place the Tabs into our tanks here, we use long-nose hemostats to help us bury them in the substrate.

Because Flourish and Flourish Tabs are broad spectrum, comprehensive supplements, they are going to contain lower percentages of the nutrients than are the nutrient specific products. Think of it this way: you can take a multivitamin and get small amounts of lots of different vitamins, or you can take an iron supplement, for example. I'll guarantee you that the concentration of iron in the iron supplement is higher than the concentration of iron in the multivitamin. Same idea applies to the product in the Flourish line.

Flourish Excel works by providing the plants with a substance that mimics photosynthetic intermediates, thus saving the plant the energy of having to go through each step of photosynthesis on its own. It basically provides carbon in the form that is needed to enhance growth, while allowing the plant to utilize its energy for growth. Therefore, it is as effective as a CO2 reactor in providing a source of carbon, while eliminating the potential for pH shifts that you may have with CO2.

[LabTest57]

What I was triyng to understand is if 0.32% of iron is good enough, because other commercial products for aquariums contain much less.

[Tech Support DD]

For some plants (and some people's tanks), 0.32% may be enough; therefore, those people may be fine to just use Flourish. However, Flourish Iron should be used in those cases where the iron requirements exceed that which can be delivered by Flourish at the recommended dose or signs of iron deficiency appear (such as short and slender stems or yellowing between veins).