# Confirm my calculations please!



## CrispyCod (6 Jun 2011)

Hi All,

Just started dosing EI, and wanted a little help confirming that my calculations are correct. 

Tank 128L

PH 6.8
GH 8-10

78W T5HO
Pressurised C02 FE method., drop checker lime green at bottom corner.



All other water conditions ok

Where in need to check is my conversion from 3 x a week to daily  (so i dont forget!) so had to modify the calculations on Cegs Article.

As Follows:

As per the article Dose 3/16 KN03, 1/16 KH2PO4, 1/2 mgSO4    3 x a week.

Add these together to get the total added per week, then divide by 7 to get a daily dose.

this works out to be (converted to decimal for ease of calculation)

0.08 tsp KN03, 0.026 tsp KH2PO4, 0.21 MgSO4 tsp per daily dose for a 20 Gallon tank.

I have a 28 Gallon, so multiply by 1.5 (close enough)

I then calculated based on a monthly solution (30 Days):

Multiply the values by 30 to get the total dose, in a 500ml solution.

3.5 tsp KNO3(ish) 1.25 tsp KH2PO4(ish), 9.5tsp MgSO4(ish).

Divide the 500ml solution by thirty to get my daily liquid dose. (approx 17ml, dosing 15ml)

50% water changes weekly.

The other thing that concerns me is the high amount of Magnesium sulphate, I havent done a carbonate hardness check on the water, should I worry about this too much and what affect would it have if it is high...?

Thanks for the help!

Chris


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## GHNelson (6 Jun 2011)

Hi 
I dont think you will have any problems adding MgSo4.
Try this new EI calculator :arrow:http://www.fluidsensoronline.com/calcul ... ive-index/ 
hoggie


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## CrispyCod (6 Jun 2011)

Thanks Hoggie,

I have tried it, but the calculator splits into 3 doses per week, and I want to dose daily (little and often),
so had to recalculate...I have multiplied it all back up again, and the quantites are close. So reasonably sure, just wanted to know I had done the math properly.

Would be nice if changing the dosing frequency could be included in the EI calculator...?

Why do you think I wont have any problems with the MgSO4? Trying to understand the reasons behind the whole thing...

Should I be measuring it? Tank looks healthy, i have good growth so far, and the fish seem relatively happy. 

The dosing I am using currently is the standard recommendation from the one of the other sponsors on here (not fluidsensor). My calculations show a lot more MgSO4, hence the question...

Cheers again,

Chris


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## GHNelson (6 Jun 2011)

Hi CrispyCod.
I dose MgSo4 in a very hard water area with a 3 to 1 ratio.MgSo4 to other Carbonates.(Not sure if this is the correct term).... :arrow: Carbonates.
I don't need too but it covers the depletion if you run a non Co2 low tec tank....less water changes.
I also dose running a Hi Tec Co2 tank....Ive never had any problems that Ive observed dosing MgSo4 in both.
Cheers
hoggie


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## CrispyCod (6 Jun 2011)

Thanks for the reply Hoggie,

So, unless someone tells me I mucked up the math, I will go ahead with the above when making the solution (next week).

Coolio.

Thanks again.

Chris


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## ceg4048 (7 Jun 2011)

CrispyCod said:
			
		

> The other thing that concerns me is the high amount of Magnesium sulphate, I havent done a carbonate hardness check on the water,


Hi,
   There is little to no relationship between Carbonate Hardness (KH) and Magnesium/Calcium levels (GH), so it's actually a good thing that you have not performed any tests and drawn any conclusion based on test results. This is one of the strongest arguments for avoiding tests kits.



			
				CrispyCod said:
			
		

> should I worry about this too much...


No, you should not worry about it too much unless you are attempting to grow a tank full of Tonina sp or are trying to breed soft water fish in that tank.



			
				CrispyCod said:
			
		

> ...and what affect would it have if it is high...?


Generally it means that you would be wasting money buying MgSO4. The reason that the amounts of suggested MgSO4 is so high is because MgSO4 does not contain a lot of Magnesium. It is mostly SO4 (80%). So in order to get adequate quantities of Mg in the tank we wind up dosing large weights so that the paltry 20% of that weight that is Mg will be sufficient.

Even if you measure you GH, it still would not tell you anything about the Mg content. That is because GH, by definition, is a measurement of the total amount of the combination of Calcium and Magnesium, but GH measurement cannot tell you how much of each comprises the value. So for example, a GH of 8 can mean that you have 140ppm of Ca + zero Mg, or, it can mean 140ppm of Mg + zero Ca, or it can mean 70ppm Mg + 70ppm Ca, or any combination thereof.

Since we would prefer to spend our hard earned money buying a twelve pack of Boddingtons Brew instead of buying a frivolous Ca test kit or an Mg test kit, we simply add MgSO4 and slowly reduce the dosages until we see some negative effects.

As mentioned, there is some probability that your GH is comprised entirely or predominantly of Mg and not the usual Ca. If that is the case, then it is possible that your plants can actually suffer a Ca deficiency. This would be a bizarre, yet plausible possibility. In most cases, our tap water GH is comprised predominantly of Ca and only small amounts of Mg. This is a grey area which each person must address. You can use resources such as your on-line municipal water report to determine the likelihood of the relative percentages of these two cations in the water, or you could take the plunge and buy either (or both) of the two test kits.



			
				CrispyCod said:
			
		

> Should I be measuring it?


No. 
This is why:==>





			
				CrispyCod said:
			
		

> Tank looks healthy, i have good growth so far, and the fish seem relatively happy.



Cheers,


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## CrispyCod (7 Jun 2011)

Clear and concise, thanks Ceg.

I am assuming from the lack of comments on the original question that my dosing regime is suitable?

Cheers,

Chris


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## ceg4048 (8 Jun 2011)

Hi Chris,
             Yes, your calculations seem quite reasonable to me. The final numbers seem typical for a 30 gallon  tank. You could even increase the KH2PO4 value by another 1/2 teaspoon and it would not be considered over the top.

Remember that these are just the baseline numbers. We do not know how efficient your flow/distribution is, or what the actual PAR levels are, or how much CO2 actually reaches the plant beds and so forth. These factors affect the required dosing numbers. Be prepared to possibly increase the values and also be prepared to lower the numbers due to possible excessive growth and desire for reduced maintenance. Do not seek to adhere rigidly to specific numbers, but instead, maintain a flexible approach to the dosing.

Cheers,


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## CrispyCod (8 Jun 2011)

Yes, understood. Just want to get a stable input, and a baseline level. so I can see the effects, I would expect to make changes over time.

Part of the reason for asking is I have recently been experiencing film on the water surface, (trapping the Co2) and after reading the various advice, and your comments about it probably being one of 'the big 3' (light, Co2/flow or nutrients). I wanted to make sure I had control of the them all.

Lighting is ok and unlikely to change. Co2 I have finally stabilised, its been a bit up and down getting it right, which has resulted in small levels of algae growth, but stable now. And flow is over the 10x mark by quite a way. Difficulty came from having a very long quite shallow tank, so 2 Koralia, one in each corner pointing slighlty towards the centre, and a spray bar against the front glass (diffusion is a CalAqua inline) seems to have sorted it. (managed to get my anubias to pearl, but nothing else.)  

So the last bit (until the next bit)    is to get the nutrient level right. Hopefully that will remove the film.

Thanks for the advice. Much appreciated.  

Chris


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