Flushing schedule

[Sativied]

This article talks about different ways to express nutrient values using either w/w or w/v.

That doc describes basically 3 different version, the first two I was referring to with:

"Do not always use the same scale" isn't just the case here. For example, yours could be a % of the bottle's contents (w/v), mine could be a % of the contents that isn't water [ w/w]? But that wouldn't explain the ratio difference...

The difference between w/w and w/v could explain the different between the 0-18-6 and the 0-18.7-6.1

"There are many ways of describing the amount of nutrients in liquid fertilisers. The NPK level in a liquid fertiliser can be referred to without taking into account the water in which it is diluted. In other words, the idea is to identify each nutrient proportionally with respect to all the elements in the fertiliser. For example, a fertiliser classified as 26-23-29 has a nitrogen content corresponding to 26% of all the elements in that particular mix. As you can see, this representation of the concentration levels is characterised by very high numbers."

[that sounds like my bottle, and one of the following would be Mick's bottle]

"Another option is to express NPK levels in terms of presence per unit of volume. A 3-3-2 liquid fertiliser, for example, is one with 3 grams of nitrogen per 100 ml of fluid. This system is referred to asweight/volume (w/v), a method that calculates only the volume into which the fertiliser substances are dissolved rather than the weight they add to the solution.

A third alternative is based on the amount of NPK present in a liquid fertiliser, a system known asweight/weight (w/w). We know that a litre of water weighs 1 kilogram, and after we mix in the liquid fertilizer components, the resulting weight is that of the water plus the weight of fertilising elements and other products, including humic acid, buffer materials etc. The result: a litre of liquid fertiliser will always weigh more than 1 kilogram."

 

[jondamon]

That doc describes basically 3 different version, the first two I was referring to with:


The difference between w/w and w/v could explain the different between the 0-18-6 and the 0-18.7-6.1

"There are many ways of describing the amount of nutrients in liquid fertilisers. The NPK level in a liquid fertiliser can be referred to without taking into account the water in which it is diluted. In other words, the idea is to identify each nutrient proportionally with respect to all the elements in the fertiliser. For example, a fertiliser classified as 26-23-29 has a nitrogen content corresponding to 26% of all the elements in that particular mix. As you can see, this representation of the concentration levels is characterised by very high numbers."

[that sounds like my bottle, and one of the following would be Mick's bottle]
"Another option is to express NPK levels in terms of presence per unit of volume. A 3-3-2 liquid fertiliser, for example, is one with 3 grams of nitrogen per 100 ml of fluid. This system is referred to asweight/volume (w/v), a method that calculates only the volume into which the fertiliser substances are dissolved rather than the weight they add to the solution.

A third alternative is based on the amount of NPK present in a liquid fertiliser, a system known asweight/weight (w/w). We know that a litre of water weighs 1 kilogram, and after we mix in the liquid fertilizer components, the resulting weight is that of the water plus the weight of fertilising elements and other products, including humic acid, buffer materials etc. The result: a litre of liquid fertiliser will always weigh more than 1 kilogram."

I remembered reading something in an article in URBAN GARDEN MAGAZINE which is what sparked my curiosity into this thread.

I must admit I'm a layman when it comes to it all.

I stick to what works for me which is a pretty basic set of nutes that I know inside and out and it gives me results that I'm happy with.


Hope the link was helpful.



J

 

[Sativied]

I must admit I'm a layman when it comes to it all.

I stick to what works for me which is a pretty basic set of nutes that I know inside and out and it gives me results that I'm happy with.

I only use basic nutes myself too, H&G AB and a little GHE FloraDuo B to change the ratio to a little less N (gets to high in my recirculating setup). Drip Clean isn't really nutes, it does what they claim it should do though, prevent salt building up in sprayers and lines and even my chiller. Can easily tell the difference when I don't use it so it's a bottle I will rebuy when I run out of (which takes a long long time).

And yes that links was helpful, thanks. Mine does not actually contain 18% P or 6% K, those are likely percentages of all elements as in the first example of that link you posted.

Which still makes me very curious to know why 18% of the total elements being P results in 0.18% of the volume or weight while 6% K results in 0.6% of the total volume or weight. It suggests K is a lot heavier than P.

 

[941mick]

I only use basic nutes myself too, H&G AB and a little GHE FloraDuo B to change the ratio to a little less N (gets to high in my recirculating setup). Drip Clean isn't really nutes, it does what they claim it should do though, prevent salt building up in sprayers and lines and even my chiller. Can easily tell the difference when I don't use it so it's a bottle I will rebuy when I run out of (which takes a long long time).

And yes that links was helpful, thanks. Mine does not actually contain 18% P or 6% K, those are likely percentages of all elements as in the first example of that link you posted.

Which still makes me very curious to know why 18% of the total elements being P results in 0.18% of the volume or weight while 6% K results in 0.6% of the total volume or weight. It suggests K is a lot heavier than P.

IDK it still seems weird to me that the numbers are identical besides the placement of the decimal...

 

[Sativied]

IDK it still seems weird to me that the numbers are identical besides the placement of the decimal...

Yes, that piece of the puzzle is still missing. I asked them about that (the ratio difference instead of just a scale difference) specifically as well in my email to them.

A possible explanation could be that is just a coincidence though and that the 0.18% is that "minimum" value determined in analysis and they are forced to list that one in the US.