Hello happyhydro,

Your product does not exactly represent a balanced or adequate formula for tomatoes as it comes. This and similar products are typically/classically complemented with other salts as calcium nitrate and (in case of need) with magnesium sulphate.

When "down-sampling" 9-15-30 to actual elemental data, typically used in hydroponic formulas, you end up with around
N = 90ppm
P= 66ppm
K= 249ppm

A (much more) balanced tomato formula would rather look like:

N= 150-160 ppm
P= 35-45 ppm
K= 240-280 ppm

To reach 160 ppm of N, with the base formula of Miller's (as in P=66, K=250), you'd need to add Miller's versus calcium nitrate in a ratio of 3.6 to 1 or in other more practical terms: 16 gr of Miller's plus 4.5 gr. of calcium nitrate per 100 liter will end up in an EC of around 2.0 mS/cm (EC) and a formulation of around 160/65/250 ppm.

Magnesium content should turn around 40-50 ppm, and complemented with magnesium sulphate in case it is not sufficiently contained in Miller's.

Important: you need to either dissolve Miller's and Calcium nitrate separately in a certain amount of water and in two steps, or mix 2 concentrates and handle them as A- and B- solution. Never mix them or let them get in contact in concentrated (either in liquid or dry) form!

Downside although the modification : an inevitable excess in P and a still high amount of Ammoniacal Nitrogen (due to the actually unlucky original product composition) will most probably end up in a pretty acidic and buffered nutrient solution (around ph 5-5.5 depending on base pH of your water).

Hope this helps!

Cheers,
Lucas

Thanks Lucas, I used this 9-15- 30 for my summer crop of heirloom tomatoes. The plants looked fine, ph held at 5.6 to 6.0, tomatoes were delicious but small and not very plentiful.I am starting my Fall tomatoes now and am using GH 1 part grow but I am looking for less expensive nutes to grow tomatoes in DWC hydro, any suggestions? Thanks alot

Well, a more balanced formula as described earlier would probably give more plentiful and better results. I was not reinventing the wheel, but referring to 'edu' and scientific recommendations that have been tested by myself for several seasons. You may keep those in mind for any choice of nutrient composition regardless of "kind", brand name or price.

As almost any "commercially available" nutrients use the same (or similar) raw materials and salts, - brand names or "descriptions" do not necessary matter or guaranty anything.

As far as I know, there are only two ways to lay hand on inexpensive, adequate and balanced, crop specific nutrients:

1. as described in the precious post: chose an inexpensive dry nutrient and modify/complement it with 1 or more salts. Best is to do so according to "recipes" of reliable sources.

Or 2. by composing your own nutrients from (very cheap) common salts and components -also following the rules and directions of either reliable sources or by using experienced growers' recommendations.

I went for 2. since my first experiments with hydroponics. That way I make extreme savings, know exactly what I have got and can modify my formulas if necessary.

PS: using Miller's 9-15-30 as it comes (only), you normally should end up with much lower pH as you mention, (if not corrected previously) except with rather alkaline base water over 7.5 or if using it in very low concentrations only.

Here is a link that might be useful: Nutrient Solution Formulation Tomatoes in Florida

If you are looking for a cheap, organic fert that can be used in a DWC hydro grow, something to consider is Tomato-tone. Part of the nitrate is not water-soluble, but enough of it is as toms do not require much nitrogen.

Mike