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Simplified measurements for mixing dry powders with water

nry

nry

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Joined
23 Oct 2007
Messages
1,225
Location
Cumbria, UK
If, like me, it is easier for you to dose your NPK by mixing it with water in advance (useful for those of us with smaller tanks, anyone else here struggle to visualise 1/32 of a teaspoon?!) here is what I believe is a teaspoon based measurement for 500ml water mixing:

KNO3 - add 6.25 level teaspoons (or 6 and a little bit more!) to 500ml of water
KH2PO4 - add 3.125 level teaspoons (or 3!) to 500ml of water
K2SO4 - add 7.81 level teaspoons (or 7!) to 500ml of water

I use 250ml bottles so I just halfed (roughly) the amounts above. I only add 10ml of KNO3 3x per week for a 250ml bottle lasts me 25 doses which is ~2 months.

I haven't weight checked these, I worked it back from the teaspoon/ml ratio on theplantedtank.co.uk and it appears to be about right from when I weight mixed. I don't have my own scales to measure 0.1g increments and have to borrow them from work. I managed to forget and forget to borrow them before my KNO3 ran out so had to work them out as above. I dose trace via Tropica Plant Nutrition so didn't work this out.

If it seems right it should be easier for newcomers without scales and perhaps for those who have scales but can't be bothered weighing things each time they mix ferts! If I am wrong in the ratios please correct me!
 
Hi,
There are plenty of ways to skin the EI cat. This post has all the data required: viewtopic.php?f=36&t=1211 No weight conversions required and everything is scaled for each person's tank size from the reference 20G tank. By the way, you can simplify things even more if you delete the K2SO4, which is completely unnecessary if you are already dosing KNO3.

Cheers,
 
So why do most EI dosage regimes suggest all three? Don't mind dropping it if I know why?

I find the tiny teaspoon fractions way too small to work out with an actual teaspoon hence I mix with water.
 
People got used to PMDD dosing with lower NO3 dosing levels and so when they switched to higher NO3 dosing with EI they carried on the potassium sulphate dosing as they had always done it. I'm a bit guilty of this as well . If you dose lower amounts of KNO3 then you will need to supplement the potassium levels with potassium sulphate, but at normal EI dosing you add 8ppm NO3 and 5ppm K three times a week which is more than enough K for the plants.

James
 
Excellent then, one less thing to do 3x per week!
 
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