# Difference in dosing calculators



## AquaDada (Jan 3, 2014)

Am I missing something here? I think this is why I am struggling with getting a good recipe as different calculators are showing completely different readings.

Notice the KNO3 as example. Why are these so way off?

This is the result I am getting from here

http://tinycalc.petalphile.com/










This is the results I am getting from the Fertilator on this site










Another thing that is not making sense is for NO3 it says the target is 10-20 ppm but, in a sticky thread on here for EI it says NO3 range 5-30 ppm

Now if I let the first calculator tell me the amount it is telling me 111.1g to even reach 6 ppm but that is not even in the recommended range of the Fertilator on this page of 10-20 ppm. Also it says I need only 8g to get to 14.4 ppm which is no where near the 111.1g the other calculator is saying to get only 6 ppm.










My tank isn't suffering but I would like to get a solid recipe so if I ever run into problems I can rule out ferts and know I am maximizing the potential with having the right solution mixed up. I do have some plants that are growing better than others and I think it is because maybe my ferts are lacking. I am injecting CO2 but another thing that I think might be hurting me is I am doing 50% water changes every other day because I was told with Amazonia substrate I needed to do water changes for the first 2-3 months 3x a week. That really doesn't make sense to me as that doesn't seem like that is enough time to allow the ferts to even take effect since the tank is being reset so often. From what I understand as long as you're doing weekly 50% WC that you really can't over fert your tank but, is it possible to under fert your tank?


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## Zapins (Jul 28, 2004)

Both calculators agree when you have them set to the same mode. You are asking the fertilator to calculate what ppm concentration nitrate will be when you add 8 grams to your 90g tank.

You are setting the http://tinycalc.petalphile.com/ site to make a solution. The 111.1g it is telling you to add is to a 500 mL amount of water. To dose your tank you will take 15 mL of liquid from this bottle and add it to your tank. The 15 mL will increase your tank's nitrate concentration to 3.78 ppm. If you add 30 mL of the liquid from the bottle you'll add 7.56 ppm nitrate to the water.

If you want to set them to calculate the same thing either set the fertilator to make a solution mode from the drop down, or set the http://tinycalc.petalphile.com/ site to "dry dosing" instead of solution mode.

Also, you have way more options if you use the http://calc.petalphile.com/ instead of the http://tinycalc.petalphile.com/ site.

As for different ranges for EI. I tend to go by the fertilator's ranges for the most part. For macro nutrients like nitrate/phosphate/potassium it doesn't matter too much what the exact concentration is since they are basically non-toxic to plants and will not cause issues when over dosed. Your goal with EI is to never reach 0 ppm at any point during the week. For my heavily planted 90g tank the plants use about 20 ppm nitrate and about 25 ppm potassium each week, and only 2 ppm phosphate. So if I dose twice a week with 20 ppm each time, and 25 ppm potassium my plants never run out of nitrate and never starve, then 50% water change and it resets everything. You can break the doses up anyway you like, so I could dose 4x a week at 10 ppm nitrate and 12.5 ppm potassium etc. or 5x or 3x, or 6, 7x whatever. As long as the plants never run out and always have enough between doses it doesn't really matter very much.


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## AquaDada (Jan 3, 2014)

Whats the best way for calculating for a solution because that is what I thought I was entering. Container is 500mL and dosing 15mL. It tells me 277g to reach 15ppm on one and the other is saying 8g just to reach 14.4g. I just need to figure out a solution for 90G using high light and CO2 and can't seem to figure it out.


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## Zapins (Jul 28, 2004)

You are asking each program to do a different task. 

Adding 8 grams to 90 gallons of water will give you 14.4 ppm. 

Adding 277g to 500 mL of water, then taking 15 mL of that solution and adding it to your tank is roughly the same thing as adding 8g directly to your tank.

277 g in 500 mL is (277 grams/500 mL) = 0.554 grams per 1 mL of this solution. If you add 15 mL you are adding (15 mL x 0.554 grams per mL) or 8.31 grams to the 90g tank, which is the same as 15 ppm.

Making a solution is not the same as directly adding dry chemical to your tank.

I have calculated it out for you. Add 140 grams to 500 mL of clean water. Then to dose your tank add 15 mL of this solution to your 90g tank. Every time you do it will raise the concentration of nitrate in the water by about 4.8 ppm (nearly 5 ppm). So if you want to add 20 ppm total to your 90g tank, you must add 4x15 mL which is adding 4x5 ppm each dose, or 20 ppm.

Do not add more than 180g of KNO3 to 500 mL of water or the KNO3 will not dissolve and it will remain undissolved at the bottom of the container.

I hope this helps. Let me know if it doesn't.


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## AquaDada (Jan 3, 2014)

Zapins said:


> I have calculated it out for you. Add 140 grams to 500 mL of clean water. Then to dose your tank add 15 mL of this solution to your 90g tank. Every time you do it will raise the concentration of nitrate in the water by about 4.8 ppm (nearly 5 ppm). So if you want to add 20 ppm total to your 90g tank, you must add 4x15 mL which is adding 4x5 ppm each dose, or 20 ppm.


I see how it works now. One figures it based on a single daily dry dose and not the overall solution of each dose. After finding the correct way to calculate it I see how it works now.

How did you come to the calculations above though? This is what I got which is a little different from the calculations above. If I understand correctly I need each dose to be between 10-20 PPM correct? If that is true I can't add more that 140g as it isn't soluble so how would I get that target. This will also be mixed with KH2PO4 & K2SO4 to make my macros solution so I can't double dose unless I take that in account for the other two. Also is 140g normal for KNO3 or does that seem like a lot for a solution? No if I went to 30 mL which is doable with these containers I use since it measures it out as 5, 15 or 30 mL it would bring me to 15.12 ppm of NO3 according to the calculator.

So this is what I have come up with according to the calculator.

500 mL container
30 mL doses

Macros M-W-F
Micros T-T-S
50% water change on Sunday

MACROS

KNO3 - 140g yielding 15.12 ppm per dose
KH2PO4 - 15g yielding 1.84 ppm per dose
K2SO4 - 140g yielding 11.06 ppm per dose (Solubility issues at this amount)

MICROS

Plantex CSM+6 - 50g yielding 0.58 ppm per dose
DTPA Fe (10%) - 30g yielding 0.53 ppm per dose

Dose this look about right?


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## Zapins (Jul 28, 2004)

AquaDada said:


> I see how it works now. One figures it based on a single daily dry dose and not the overall solution of each dose. After finding the correct way to calculate it I see how it works now.


Yes.



AquaDada said:


> How did you come to the calculations above though? This is what I got which is a little different from the calculations above. If I understand correctly I need each dose to be between 10-20 PPM correct?


The ranges on the Fertilator are approximately what you should have in the tank at all times. This is not the same thing as dosing 10-20 ppm each time. If you dose 3x a week at 20 ppm each dose you'll have up to 60 ppm in the tank, this is a bit high. Plants do not really use anywhere near this amount of basically any nutrient, this is why I had the program figure out smaller doses of about 5 ppm each dose. So you can dose 3-4x a week and have finer control over the amount you are dosing.



AquaDada said:


> If that is true I can't add more that 140g as it isn't soluble so how would I get that target. This will also be mixed with KH2PO4 & K2SO4 to make my macros solution so I can't double dose unless I take that in account for the other two.


Yes, this is generally why I weigh a certain amount of fertilizer out and dump it right into the tank. Other people like making solutions and seem to eye ball the amounts they need and mix it into the solution. You could also make solutions for each individual fertilizer if you want more control over the whole process.



AquaDada said:


> Also is 140g normal for KNO3 or does that seem like a lot for a solution? No if I went to 30 mL which is doable with these containers I use since it measures it out as 5, 15 or 30 mL it would bring me to 15.12 ppm of NO3 according to the calculator.


Yes, if you are making a solution 140g is how much you'd want to add to the solution. Because you will only be taking a small portion of the 140g and adding it to your tank each time you dose. I'd recommend figuring out a dose (or using the numbers from the above post) that allows you to add a smaller amount of nitrates each time you dose the tank. If every dose gives you 15 ppm, then you wouldn't want to dose nitrates more than twice a week. This will give you a weekly total of 30 ppm, which is on the higher side of dosing (which is ok).



AquaDada said:


> MACROS
> 
> KNO3 - 140g yielding 15.12 ppm per dose
> KH2PO4 - 15g yielding 1.84 ppm per dose
> ...


These values per dose seem a bit high. If it were me making a solution I'd try get it so that each dose gives you about 5 ppm nitrates, 0.5 ppm phosphates, and about 10 ppm potassium (you also have to realize that your KNO3 and KH2PO4 will add some extra potassium to the tank on top of K2SO4).

For micros, you want to be really careful with CSM+B, while the macros (nitrogen/phosphorous/potassium) don't really cause issues when dosed in excess micro nutrients do and can quickly reach toxic concentrations. Reduce the amounts you mix up for CSM+B so each dose gives you about 0.1 ppm. If you dose this 3x a week like you want to you'll end up with 0.3 ppm which is safe. Anything approaching or over 1 ppm CSM+B brings you into the "danger" zone where depending on other factors, like what is in your tap water, you may reach toxic values for certain nutrients.

The Iron dose is also on the high side. I'd reduce that to about 0.1 ppm each dose as well, giving you a total of 0.3 ppm if dosed 3x a week. When you add up the iron CSM+B is giving you per week at the above mentioned concentrations (0.3 ppm) and the iron from Fe DTPA (0.3 ppm), you will be dosing 0.6 ppm iron every week, which is an acceptable and safe amount.

Post back your final values before you mix up a solution.


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## Zapins (Jul 28, 2004)

I was just plugging in a few numbers on the fertilator and found another method that could work for you.

*For dry dosing:*
If you add for one "dose":
3 g KNO3, 
0.3 g KH2PO4, 
4 g K2SO4 and 
0.5 g CSM+B

This will give you, about 5 ppm nitrates per dose, 0.6 ppm phosphates, 9 ppm potassium, and 0.1 ppm iron each time you add the above amounts directly to your tank water.

You could dose this 3-4x a week and you'd be within recommended EI ranges. It also gives you a lot of room to make adjustments if you want to, you can add more or less and do not have to worry about mixing up an entire solution with each of the chemicals in it.

*For a 100 mL solution:*
Alternatively you could make a solution based on the above values, just multiply them by 10 and add them to 100 mL of water. Then each *10 mL* of liquid you take out of the solution mix will give you the dose described above.

So 30g KNO3 in 100 mL, 3g KH2PO4 in 100 mL, 40g K2SO4 in 100 mL, 5g CSM+B in 100 mL, then *10 mL* of the solution will give you the ppm values I mentioned above.

The only problem with this solution is K2SO4 won't dissolve 40 grams into 100 mL, it will only dissolve 12g into 100 mL max, so you'd need to have two solutions for macros, one solution with both the K2HPO4 and the KNO3 together (30g KNO3, and 3g KH2PO4 in 100 mL), and then another solution with just 12g K2SO4 in 100 mL. Then you'd need to add about *35 mL* of this K2SO4 solution to reach the above recommended ppm level.

*For a 500 mL solution:*
If you are really gun-ho about large solutions you could scale that up to 500 mL bottles by multiplying the original values by 50, so 150g KNO3 in 500 mL, 15g KH2PO4, 25g CSM+B then your dose would be *10 mL*of each of these solutions to give you the above ppm values in your big tank.

For K2SO4, you can't dissolve the necessary 200 g into 500 mL of water so you'd have to dissolve 60 grams into 500 mL, then add *35 mL* of this solution to your 90g tank and it will give you the above recommended ppm values.

Hope this helps.


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## AquaDada (Jan 3, 2014)

Zapins said:


> These values per dose seem a bit high. If it were me making a solution I'd try get it so that each dose gives you about 5 ppm nitrates, 0.5 ppm phosphates, and about 10 ppm potassium (you also have to realize that your KNO3 and KH2PO4 will add some extra potassium to the tank on top of K2SO4).


This is what is confusing and the calculators don't account for. According to another thread stickied on this board it states this.

EI target ranges
CO2 range 25-30 ppm
NO3 range 5-30 ppm
K+ range 10-30 ppm
PO4 range 1.0-2.0 ppm
Fe 0.2-0.5ppm or higher
GH range 3-5 degrees ~ 50ppm or higher
KH range 3-5

The way I understand EI from Tom Barr is it is a method that provides excess nutrients so they are available for the plants. That is why the need for 50% water change on the 7 day to reset the system. So for example if I was only dosing 5 ppm nitrates in a heavily planted tank those nutrients would be gone by the end of the day if not by the next dosing of Macros a day later and possibly starving plants. Tom Barr states it is better to over dose than under dose so those nutrients are there since it is getting reset with a water change. It is to much understand I should be maintain that range above through the entire week and only dose 5 ppm KNO3 seems rather low. How does one calculate for this because all the calculators don't account for this. and anything lower says it's not in range and to increase my dosing or add more ferts to the solution.

These calculations were based on a daily dosing that keeps it within the recommended range from the calculators. Dosing 15ppm 3x a week isn't going to equal 45ppm because plants are up taking nutrients so it will never get that high. You are keeping excess nutrients in the water column for plants to use when they need them until your water change and you reset your system and it starts all over again. That is how I understand as it was explained for Tom Barr and through my research. If this is wrong please correct me because other wise this makes no sense and there has to be a much easier method of calculating. ferts for a solution. My containers are 500 mL and the dosing amounts ether have to be 15 or 30 mL. Other wise I can't measure them accurately and quickly and for me a solution is a lot easier for me because of work and kids, and family. 10 seconds and I am done.


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## Zapins (Jul 28, 2004)

Yep you seem to have the gist of it right. Better to slightly over dose than under dose.

The way to do it is to dose 20 ppm in an initial dose to start the tank up, then add 5 ppm 3-4x a week to maintain what the plants use up. 

Your plants in a 90g tank will not use more than 20 ppm nitrate/25 ppm potassium in a week even if the tank is heavily planted.

You can dose 3x15 ppm KNO3 per week if you'd like, that will be 45 ppm per week (assuming your tank is heavily planted, you have very high lighting and CO2, your plants will use up about 20 ppm per week). Leaving an excess of 25 ppm KNO3 each week. If you do 50% water changes per week, the most the tank's nitrate levels will reach after several months is 2x the initial dose, so you won't have more than 90 ppm at any given point. Which is fairly high if you plan on keeping fish. Stunted growth and other abnormalities tend to happen above about 30 ppm nitrate. 

Fertilizer dosing using EI is not an exact science, it is an art. The values you read about and my estimations are all ball park figures, that allow you to play with the values if you see your plants need more or less. I think you need to mix up a few solutions and see what works for you. The worst that can happen is you either don't dose enough, your plants develop deficiencies, then you add more and they grow out healthily in a week, or you dose too much and cause a plant toxicity or your fish to stunt, in which case you just reduce the dose to an appropriate level. If you'd like to try over dosing macros like N, P, K, then that is fine, but do not do this with CSM+B it is much more likely to cause toxicities.

There are many ways to dose, that is why it is called "estimative index."

Let us know what you decide to mix up and how it goes!


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## AquaDada (Jan 3, 2014)

What I don't under stand is what is the point of the scale if it is not accurate? This is based on dosing 2-4 times a week in a 500 mL container 30 mL. It kind of seems misleading it it is not right and there is no explanation of the calculations.










Is there a chart for plant uptake limits and a calculator for long term effects of those dosing other that that plant uptake chart that doesn't make any sense ether because there is no explanation?


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