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Low ph for plants ?

Discussion in 'Planted Chit Chat' started by concentration, Mar 19, 2017.

  1. Byron

    Byron Member

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    Having read through this thread, I may be able to clear up a few misconceptions. Because I believe it is always better to see the full picture I will repeat some things already said.

    First, aquatic plants need sufficient light intensity to drive photosynthesis, and they need sufficient nutrients in balance. The "balance" aspect is crucial. Too much light, or too little, or too many nutrients, or too few, and plants cannot photosynthesize sufficiently (or at all, depending) and algae will become problematical.

    Nutrients are 17 in number. There are macro nutrients (more of these is needed) and micro nutrients (less).

    GH is general hardness, which involves minerals but primarily only two of them, calcium and magnesium. Other minerals can contribute to the GH but normally, especially in tap water where laws regulate the levels of heavy metals and such, it is calcium and magnesium. So GH alone is not going to tell you if all necessary nutrients are present. The other thing to keep in mind always, if fish are to be kept in the aquarium with plants, is that plants are much more adaptable than fish when it comes to GH, KH and pH. We can easily supplement minerals for plants but if the GH is wrong for the fish species the fish will have serious issues. Fish first.

    I have source (tap) water with a GH and KH almost zero. I keep fish that need this. I have plants in all my tanks, and I use substrate fertilizer tabs for some, and liquid fertilizer for others, primarily. The liquid obviously benefits all plants.

    With a GH around 3 to 4 dGH, you are ideally situated for most plants. Stay with soft water fish.

    Now, the GH as I said above is primarily calcium and magnesium. You may have to add the other nutrients, depending upon the plant species; different species have different needs for light and nutrients. Fish foods contain all nutrients the plants can use (from fish excrement in the substrate as it is broken down by bacteria) but again depending upon species these may or may not be sufficient alone.

    Iron was mentioned. It is generally not safe to add individual minerals like iron, unless you know the proportion of all of them. It is a fact that aquatic plants require their 17 nutrients in a rough proportion to each other; too much of some of them can cause plants to shut down assimilation of other nutrients. So it is important to not overdose any one nutrient. Red leaf plants need more light intensity than green leaf plants, and this is usually where red plants fail. The colour of plant leaves is due to the light being reflected, so red leaf plants are reflecting red light. But red light is also crucial for photosynthesis, along with blue, but red is the more important of the two. So, red plants will need brighter lighting than green plants, generally. [There are always exceptions.]

    The pH is generally unimportant to plants, though again not to fish. Most aquarium plants come from regions with very soft water (zero GH and KH) and generally an acidic pH (it can range from the 3's up to the 6's, but it is on the acidic side (below 7) in most places. There are exceptions. Some plants, like Vallisneria, occur in waters with higher mineral content; they even occur in the African rift lakes which is the hardest and most basic (above 7) pH of any fish we keep. These plants can use bicarbonates, which brings me to the carbon (CO2) issue.

    Carbon was mentioned. Plants prefer this as CO2. Some can only use CO2, others (like the Vallisneria) can also use bicarbonates. But CO2 will be used by all plants regardless. Natural CO2 occurs from the normal continual respiration of fish and plants and some bacteria species. But there is much more produced by the breakdown of organics, which is primarily in the substrate. This is often much more than many people realize. Before jumping into thinking you need diffused CO2, you need to asses your light, intended plant species, and fish. The more fish and the more you feed them, the higher the organics and thus more CO2. With many plants this is adequate. Lighting as I said at the beginning drives photosynthesis, so it has to be sufficient for the plant species and balanced with the CO2 and other nutrients.

    I personally don't recommend soil substrates. But to answer a couple questions...yes, a soil substrate will increase the CO2 because it contains organics that get broken down by bacteria. This also produces ammonia...any decomposition of organic matter produces ammonia and CO2. Fish also respirate both. So having soil can indeed increase ammonia, and during the first six months or so, it is very possible to literally poison fish with excess ammonia.

    I can expand on the above if asked.

    Byron.

     
    #16 Byron, Mar 19, 2017
    Last edited: Mar 19, 2017
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  2. StevenF

    StevenF Member

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    These numbers are excellent for a soft water tropical aquarium.

    GH is a measure of calcium and magnesium in the water nothing else. Calcium and magnesium are macro nutrients for plants and they will slowly consume it. So the only issue you have is to make sure it doesn't drop much between water changes. Your GH is also at the minimum level required for shrimp survival. IF you GH drops too fast you might have to do more water changes to keep it stable or add a small amount of GH booster such as Sachem equilibrium. Another option is to add one or two decorative sea shells to our tank. These are mainly calcium carbonate and will slowly over years dissolve in your water. and help maintain GH and PH at your current levels.

    While many people use soil or special plant substrates in aquariums they are not needed for good plant growth Furthermore within a year in most cases most of the mineral content will have been lost do to water changes. When that happens you either need to remove the substrate or use fertilizers. Given the expense of special plant substrates and the occaitonal Ammonia problems people report with them, I am staying with ordinary gravel and Sachem Flourish comprehensive fertilizer.

    As to liquid CO2 boosters are fertilizers they can be used but keep in mind it is a topic chemical. If you overdose the tank you could kill your fish or even your plants. Some plants are especially sensitive to it and will die. I have found it is not necessary. In my opinion it is more important to fertilize the water with all the macro and micron minerals plants need. CO2 is only really needed if very fast plant growth is needed. Instead aerate your water more than normal to help insure CO2 levels stay normal. My filter spay bar is located about an inch above the water surface when the water hits the surface it carries a lot of air down with it.
     
  3. hobby5

    hobby5 Member

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    Lets add my 2cents :p

    GH only measures calcium and potassium ions. Fertilizer contains many different ions too.

    If the main focus is fish, read on:
    Plants are beneficial for your fish. So it is always good to have them. There are many easy plants which will grow in a low-tech setup, without any CO2 in a wide range of ph, KH, GH and temp. The only thing which is important is light. But too much light might also be counterproductive. If algae and or growth issues arise you have some nutritional imbalance and can help those by adding specific(!) fertilizers depending on the problem.

    If you think about it, in nature there is no addition of CO2 either ;)

    There is no need for soil in an aquarium. Many plants will take up nutritients through their leaves and not through the roots. Best substrate is rounded inert quartz sand. There are root fertilizer tabs for those plants which need it.

    As already mentioned above, not all plants thrive under all conditions and it is not always easy to determine all factors. So my approach always is, to get as many different plant species for the start as possible and see which thrive and which not. Importantly, get many fast growing plants for the start.
     
  4. concentration

    concentration Fish Fanatic

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    Thank you for your advice, in fact that release me from alot pressure trying to make everything right or perfect

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  5. concentration

    concentration Fish Fanatic

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    That's very informative and thank you , that help me cleared alot of issue and I guess I should keep it simple and see how it goes

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  6. concentration

    concentration Fish Fanatic

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    Thank you that helps a lot, I guess I will work on it and see how's the progress going and then come back for more info

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