AlexVojProc
Seedling
What is the Hoagland solution?
The Hoagland solution is a nutrient solution developed in the 1930s-1950s. It was originally developed by Hoagland and Arnon for use in hydroponics, as detailed in their 1950 paper "The water-culture method for growing plants without soil". Since hydroponics is the growing of regular plants in an inert substrate, the thought occurred to me that the Hoagland solution may be appropriate for growing aquatic plants. The solution provides all the nutrients necessary for plant growth, and works well for growing a variety of plant species: in the scientific world, it is widely used to prepare plant cultures.
Isn't this just like EI dosing, but from the 20th century?
Compared to EI dosing, the Hoagland solution is very concentrated for aquatic plants: it includes 610 mg/L in nitrate alone. But, diluted to a 1/10 scale, it doesn't seem too extreme, especially for tanks without livestock. At this concentration, it would contain:
The experiment
To me, these ratios seem a crazy change from EI, which is very familiar at this point. But, I'm considering trying this out on a new 240L high-tech tank. 30 ppm CO2, high light, all the usual. I might also consider adding pentanedial (glutaraldehyde/generic Flourish Excel). Does anyone have any suggestions, warnings, revisions or predictions before adding plants?
Measurements so far
I've filled the tank and added the above fertilisers. The worst case scenario is that I do a 100% water change, which isn't too painful. Since I don't have access to any proper equipment, I'm going to be using API's test kits. Here are the relevant results in the empty aquarium:
The Hoagland solution is a nutrient solution developed in the 1930s-1950s. It was originally developed by Hoagland and Arnon for use in hydroponics, as detailed in their 1950 paper "The water-culture method for growing plants without soil". Since hydroponics is the growing of regular plants in an inert substrate, the thought occurred to me that the Hoagland solution may be appropriate for growing aquatic plants. The solution provides all the nutrients necessary for plant growth, and works well for growing a variety of plant species: in the scientific world, it is widely used to prepare plant cultures.
Isn't this just like EI dosing, but from the 20th century?
Compared to EI dosing, the Hoagland solution is very concentrated for aquatic plants: it includes 610 mg/L in nitrate alone. But, diluted to a 1/10 scale, it doesn't seem too extreme, especially for tanks without livestock. At this concentration, it would contain:
- Nitrogen (as KNO3 and CaNO3) - 21 mg/L
- Potassium (as KNO3) - 24 mg/L
- Calcium (as CaNO3) - 20 mg/L
- Phosphorus (as KH2PO4) - 3 mg/L
- Sulphur (as MgSO4) - 6 mg/L
- Magnesium (as MgSO4) - 5 mg/L
- Boron (as H3BO3) - 0.5 mg/L
- Iron (as Fe-EDTA) - 0.5 mg/L
- Manganese (as MnCl2) - 0.5 mg/L
- Zinc (as ZnSO4) - 0.05 mg/L
- Copper (as CuSO4) - 0.02 mg/L
- Molybdenum (as Na2MoO4) - 0.01 mg/L
The experiment
To me, these ratios seem a crazy change from EI, which is very familiar at this point. But, I'm considering trying this out on a new 240L high-tech tank. 30 ppm CO2, high light, all the usual. I might also consider adding pentanedial (glutaraldehyde/generic Flourish Excel). Does anyone have any suggestions, warnings, revisions or predictions before adding plants?
Measurements so far
I've filled the tank and added the above fertilisers. The worst case scenario is that I do a 100% water change, which isn't too painful. Since I don't have access to any proper equipment, I'm going to be using API's test kits. Here are the relevant results in the empty aquarium:
- My first worry was KH, since the only buffer in here is the potassium dihydrogenphosphate (KH2PO4). I'm aiming for 3 dKH, but getting 1-2.
- This might be because of my low target pH of 6.5, although I'm getting 6.8. The higher pH may be because I made a mistake and dosed 4 mg/L ammonia, which is basic, as I forgot what I was doing and thought I was cycling the tank. Water changes should even this out eventually.
- Nitrate is at 50 mg/L.
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