Atami - Premium Plant Powder Hydro

A chelated bio-mineral base nutrient in powder form for rockwool, clay pebbles and other inert media, in a 1 kg bag. Dose 0.5 to 1 gram per litre of water, measured out on EC.

An inert medium buffers nothing, and that changes everything

Rockwool, clay pebbles and perlite supply no nutrition of their own and hold nothing back either. They are there to bring water and air to the roots, and that is all.

That has one large consequence: the nutrient solution you mix is exactly what the plant gets. There is no buffer in between topping up a feed that was too light or flattening one that was too heavy. Where soil still gives you some slack, here that slack is gone.

In a sense that makes the work easier, because nothing invisible is going on in the pot. What you measure is what is there. But it also makes the measurement matter more: on an inert medium your EC meter is not a check after the fact, it is the instrument you dose with.

So Atami's arithmetic figure is directly usable here: every 0.1 gram raises the EC of a litre by 0.09 mS/cm. Set your target, subtract your tap water EC, and divide by 0.09 to know how many tenths of a gram per litre you need.

Why drying out punishes you faster here

Because the medium holds nothing, it does not hold water the way soil does either. A pot of soil that gets skipped for a day lives off its own reserve. Rockwool that dries out has no reserve.

On top of that, the solution left behind concentrates as the water evaporates, so a block that gets too dry is not only short of water but also sitting at a higher EC than the one you mixed. That is the ordinary explanation for burn symptoms at a dose that looks correct on paper.

Watering more often and in smaller amounts is therefore nearly always better on an inert medium than less often and more.

What is in it

Atami describe the range as chelated mineral plant nutrients in powder form. Alongside calcium it contains magnesium, in Atami's words the key element in photosynthesis. The chelate keeps the metals available for uptake, including at a pH that is not quite right.

It is a one-component feed for the whole cycle, added from the growth phase onwards and given daily. Atami recommend their bio-stimulators alongside it.

The right version

There are three Premium Plant Powders and they are not interchangeable: this one for inert media, one for soil and one for coco. That distinction sits in the composition and not just on the label, so the wrong bag is not a small deviation but a different ratio from the one your medium asks for.

Store the bag closed, dark and at room temperature. The packaging is light tight.

Technical Specifications:

• Type: chelated bio-mineral one-component nutrient in powder form
• Manufacturer: Atami
• Substrate: rockwool, clay pebbles, perlite and other inert media
• Contents: 1 kg
• Dosage: 0.5 to 1 gram per litre of water
• EC: every 0.1 gram raises EC by 0.09 mS/cm per litre
• Period: from the growth phase, throughout the cycle
• Frequency: daily with the irrigation water
• Contains among others: calcium and magnesium
• Storage: closed, dark, at room temperature

Frequently asked questions

How many grams per litre?
Between 0.5 and 1 gram. Work it out precisely with the EC figure: 0.1 gram adds 0.09 mS/cm per litre, so you derive the weight from your target minus your tap water EC.

Why does EC matter more here than in soil?
Because an inert medium buffers nothing. What you mix is what the roots get, with no correction from the substrate.

I am getting burn symptoms although my dose is correct.
Look at drying out. If water evaporates from the block, the EC in the medium climbs above the one you mixed. Watering more often and in smaller amounts usually solves it.

Can I use the Soil or Coco version if this one runs out?
Better not. The three versions differ in composition and are matched to what the medium does and does not do.

Does it work in a recirculating system?
It is a base nutrient for inert media. Under recirculation your EC and your ratios drift over the run, so measure the tank more often and refresh it in good time.