Thats a useful comparison chart for reference! Thanks for posting it.
Yeah, for larger planted tanks (> 3ft size) it definitely makes alot more sense to go with dry ferts, saves alot over the long run.
Nov 2022 Update in red
Recently did a comparison of Nitrate fertilisers and the cost per dose. Just sharing my findings:
- Seachem Nitrogen $15.50 $23.50 per 500ml ($0.31 $0.47 per 10ml)
- AquaVitro Synthesis $20 $18.60 per 350ml ($0.57 $0.53 per 10ml)
- KNO3 5% Solution $63 per 5000ml ($0.13 per 10ml)
- Ca(NO3)2.4H2 dry $9.80 per 500g ($0.20 per 10g)
Calculations based on my tank water volume (600l) to reach approximately 7.5ppm NO3. Doses are rounded to human-doable doses.
(For those viewing via Tapatalk, below is a table. You may need to use browser to view it properly.)
Fert Dose Results Cost Seachem Nitrogen 70ml 7.7ppm NO3, 1.94pm K $2.17 $3.29 AquaVitro Synthesis 35ml 8.21ppm NO3 equivalent (see 25 Nov 2017 update below) $2.00 $1.86 KNO3 5% Solution 150ml 7.67 ppm NO3, 4.83ppm K $1.89 Ca(NO3)2.4H2 Dry 1.5tsp (~9.4g) 8.23ppm NO3, 2.66ppm Ca (+0.37 dGH) $0.18
Of course, dosing with dry is always very much cheaper. My concern with Calcium Nitrate was with raising dGH with the Ca, but never did the calculations. At this dose, 3 x a week, that's raising by ~1dGH a week, should be ok with weekly water change.
KNO3 is a pain to buy and is only slightly cheaper than dosing with Seachem and AquaVitro.
Ca(NO3)2.4H2 is still a pain to buy, but at least it's really affordable.
For reference:
600l is a 6'x2'x2' tank (accounting for sump, soil, hardscape, etc)
A standard off-the-shelf 3' tank would be roughly 160l.
** Update 25 Nov 2017
It turns out that AquaVitro Synthesis uses urea, ammoniacal sources and nitrates for N.
From Seachem website:
The values above were calculated using the RotalaButterfly.com calculators and they already accounted for the NO3 equivalent.Synthesis is a concentrated (32,000 mg/L N) nitrogen source. Synthesis is unique in that it provides nitrogen in all three forms. Approximately 50% of the nitrogen in Synthesis is derived from an organic source (urea), while the remaining nitrogen splits at about 25% each from nitrate and ammoniacal sources.
...
Use one inner capful (7 mL) per 250 US gallons (950 L) twice a week (or as needed). This dose increases total nitrogen by 0.24 mg/L. This is the same amount of nitrogen that would be present if all nitrogen were present in the nitrate form at 1 mg/L. Because not all nitrogen is in the nitrate form, you will measure a 0.25 mg/L nitrate increase immediately after dosing.
However, you may not need to dose so high as urea is better utilised by plants then NO3.
Last edited by vinz; 23rd Nov 2022 at 16:44.
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Thats a useful comparison chart for reference! Thanks for posting it.
Yeah, for larger planted tanks (> 3ft size) it definitely makes alot more sense to go with dry ferts, saves alot over the long run.
Just added the cost per 10ml/10g for others to easily estimate their doses.
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Urea is super efficient/cheaper, and I use it instead of Calcium nitrate.. but requires a little more care when dosing
I don't mind having more calcium in the tank; some plants/shrimp prefer it. It's the carbonates/KH that softwater plants dislike, having a higher GH otherwise is fine.
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Hmm I don't think so, there isn't a CO3- component to the ferts above. The main reaction we may see is that CaNO3 can bind with sulphate salts to form a precipitate => Calcium sulphate. So if you mix K2SO4 and CaNO3 in high concentration, you get KNO3 in solution with a white precipitate of CaSO4. However in normal dosing in our tanks we don't see this due to the dilution.
The main way we get carbonates in the tank is through using limestone (grey rocks/seiryu), coral chips/sand. Some commercial ferts contain carbonates; i.e. ADA, which uses potassium carbonate as a potassium source.
Ah ok. I figured there shouldn't be since there's no carbonate in any of the stuff we put in. Misunderstood your statement.
Was wondering about the K2SO4 and CaNO3 interaction as I came across that when I was reading up on CaNO3. Thanks for clarifying. I hadn't gone on to check on that yet.
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Last edited by aza; 15th Jan 2017 at 18:04. Reason: Spelling
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Hi,
Just wanted to share my own experience as an added reference.
I have a 5ft tank with sump. Total volume approximately 520 litre. I dose 1 teaspoon of dry calcium nitrate three times a week and had been doing that since Jun 2016. I changed water once at week at 50%.
I measure my gH once awhile. Usually before water change and after water change.
The gH from my tap is around 8 to 9. When I measured the water in my tank recently in Jan 2017 - it is also 8 to 9. So my conclusion is that the amount of calcium nitrate that I add did not change the gH.
As you mentioned, I think if the water change is large enough it should be ok.
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^that's right....
oh ya forgot to add... the most cost effective nitrate fertilizer is actually Urea, as it contains ton of nitrogen by weight and ammonia form nitrogen is more easily absorbed by plants. But use with care
Carbonates (KH / CO3 / HCO3 ions) are different from Ca/Mg. The former refers to alkalinity, the later contributes to general hardness (GH). Soft water plants (blood vomit, toninas) are sensitive to alkalinity, not hardness for the most part. While most plants don't fancy very alkaline water... (14dKH +) below that, most do fine except for select soft water species.
Original post updated for Nov 2022.
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