Calculating dosages of fertilizer elements for a planted ta

[squall99e]

Hi, the link below is the calulated dosage of feritlizer element.
I wasn't too sure (the amount of water to mix with: ml) mean?
Does this water refer to the one dissovling with the fert before pouring into the tank?

http://www.csd.net/~cgadd/aqua/art_p...osage_calc.htm

[squall99e]

10 teaspoons of KNO3 mix with 100ml water to 50 gallons add 1.81ppm to the tank

10 teaspoons of KNO3 mix with 500ml water to 50 gallons add 0.36ppm to the tank

Does this 400ml make such a big difference in a 50 gallons tank?

I would not want to encourage a bba comeback by dosing wrongly.

[PeterGwee]

Amount of water to mix with: ml <----- This is the amount of water you want your stock solution to be.

Example, for potassium nitrate...2 tsp of KNO3 to 500ml(amount of water to mix with)..each ml of that 500ml stock solution would yield 0.18ppm of nitrate. If you want to dose dry, simply put the amount of water to mix with as 1.

[squall99e]

Peter
OIC thanks for your fast reply.

[subxero]

----------------
On 7/21/2003 9:59:36 PM

Amount of water to mix with: ml <----- This is the amount of water you want your stock solution to be.

Example, for potassium nitrate...2 tsp of KNO3 to 500ml(amount of water to mix with)..each ml of that 500ml stock solution would yield 0.18ppm of nitrate. If you want to dose dry, simply put the amount of water to mix with as 1.


----------------

From the site, for example mixing 10 teaspoons of KNO3 to 100ml of water would yield 1.81ppm of nitrate per ml. And for a tank size of 50 gallon,the suggested target level is 5ppm Nitrate. Does it mean that I should only dose about 2.5ml each week?

Thanks

[PeterGwee]

Yup, its about there..maybe 3ml. But 10 tsp of KNO3 in only 100ml of water is not good. You would have trouble dissolving it fully as the salt concentration is too saturated in such low volume of water.

[theodore]

How much to dose will depend on how fast your NO3 gets depleted. For example, if your tank's NO3 level drop by 10ppm in 7days then you may find yourself dosing 6-8ppm, twice a week to prevent it from dropping to zero. If your tank's NO3 level drops by a mere 2ppm per week, then a dose of 3-5ppm, once a week would suffice. Lastly, if you tank's NO3 rises over time, you can forget about dosing KNO3 altogether.

[subxero]

I get the picture...

Thanks.. Peter..

[squall99e]

Hi
I just found out that the fertilizer caculation from Chuck's Plant page is not mean for our local product from HPC.

KH2PO4 For HPC K 28% and P 22%
For Chuck K 30.2% and P 69.8%
KNO3 For HPC K 38% and N 13%
For Chuck K 38.7% and N 61.3%

I have confirmed with HPC through email.

[theodore]

Wondered why the %s don't add up to 100% for the HPC products? That's 'cos 22% is for P (in HPC's product analysis) but Chuck's 69% is for PO4. Need to compare apples to apples mah.

Your next question would be why there is still a small 1-2% difference even when you compare apples with apples. Ans = Purity. Chuck's %s are accurate if the product is 100% pure. You can verify that by doing some simple calculations off the periodic table.

Conclusion : Using Chuck's calculator is still the easiest way to estimate the amount of K, NO3, PO4, etc you are adding to your tank. After all, what makes you so sure that you are adding exactly 10 teaspoons of a compound to exactly 500ml of water when you prepare the stock solution? Agar agar lah.

[bclee]

KH2PO4 will be KH2PO4 and make up of the same component not matter who supply them. The only thing that differs is the purity.

You can simply calculate the % by using the atomic weights.

K - 39
H - 1
P - 31
O - 16

So,
KH2PO4 - 39+(2x1)+31+(4x16) = 136

K% - (39/136)x100% = 28.7%
P% - (31/136)x100% = 22.8%
PO4% - ((31+4x16)/136)x100%=69.9%

Then adjust the number base on the purity you should get the composition %.

(Chuck's value is for KH2 not K. KH2 makes no sense anyway.)

BC

[squall99e]

[] On second look, it phosphorous 22% in HPC and 69.8% phosphate in Chuck's page.
Thanks for your help.

[stressed]

Hi Everyone,

I am very konfused....can someone please help.

I tried using "Chuck's" Page...but probably before I proceed, I must declare I am a total nerd in this topic so need help.

When I tried checking up on KH2PO4, it is only calculating the Phosphate..how is that so? What has happened to the KH2?

Try to help me okie......

[vinz]

Stressed,

Don't stress... the reason is because we are usually only interested in how much PO4 it will raise in our tanks. At the levels we dose KH2PO4, K is negligible vs the 20 to 30ppm levels required.

[niko]

I personally really like Chuck's calculators.

But you need to double check the numbers that you get using these calculators.
I did and I found that the calculator gives a different numbers from what I actually get per gallon. I don't think Chuck is wrong. I attribute the difference to the chemicals that I use - probably not as pure as they need to be.

Testing and finding how much fertilizers to use is very easy. Just mix say 1 leveled teaspoon of KNO3 in 100 ml. of distilled or drinking water (has no Nitrates). Stir very well. Than add say 2 ml. of your KNO3 solution to 1 gal. of distilled or drinking water. Shake well and test for KNO3. That way you will now how much will the NO3 increase in 1 gal. of water. Do your calculations for the actual aquarium using the numbers you just found.

Compare with Chuck's calculator and you may see a difference. Again - I do not think he is wrong, I belive it's the chemicals that we use.

--Nikolay