Bio G Power - PK 13+14

A concentrated mineral bloom booster with 13% P2O5 and 14% K2O, for the peak weeks of flowering. 1 to 1.5 ml per litre, given daily with the irrigation water.

The cal-mag problem in week five often comes out of this bottle

A recurring pattern: the grow is going well, the PK goes in during week four, and in week five symptoms appear that look like a calcium or magnesium deficiency. The usual response is to add cal-mag, and that only half works.

The cause is that a PK booster is first of all a large potassium dose. Potassium, calcium and magnesium are all taken up as positively charged ions and compete for the same uptake sites at the root. Push the potassium up sharply and calcium and magnesium lose that contest, even when they are present in the tank in ample quantity.

What you are seeing is not a shortage in your solution but displacement in uptake. Adding more cal-mag therefore only goes so far: you raise the concentration on one side while the displacement remains, and your EC climbs further in the meantime.

The workable approach is the other one: keep your PK dose at the bottom of the range rather than the top, and keep it short. The dose causing the deficiency is the same dose you are trying to compensate for.

The peak weeks, and why it is a window

Bio G Power place this product in the peak weeks of flowering, usually somewhere from week four through week six, daily with the irrigation water.

That window is not arbitrary. Early in flowering the plant is still stretching and setting flowers, and a heavy phosphate and potassium dose is wasteful to harmful then. Late in flowering uptake falls away and most of what you give stays behind in the medium. In between, when the flowers are building volume, demand is at its highest and the dose actually ends up where it is meant to.

Dosing

Mix 1 to 1.5 ml per litre of water, which at most is roughly 1 to 660. When in doubt stay at the bottom: the difference between 1 and 1.5 ml is a third more potassium in your tank, and that is exactly the margin in which the displacement above starts to matter.

Measure your EC after adding and pull your base nutrient back if you go over your target. Store the bottle tightly closed somewhere cool, dark and frost free.

Available sizes

Technical Specifications:

• Type: concentrated mineral PK bloom booster
• Manufacturer: Bio G Power
• Composition: 13% phosphorus pentoxide (P2O5) and 14% potassium oxide (K2O)
• Dosage: 1 to 1.5 ml per litre of water, up to roughly 1 to 660
• Period: the peak weeks of flowering, typically week 4 through 6
• Frequency: daily with the irrigation water
• Note: a high potassium dose displaces the uptake of calcium and magnesium
• Substrate: soil, coco, hydro and aeroponic
• Storage: tightly closed, cool, dark and frost free

Frequently asked questions

I have seen cal-mag symptoms since I started giving PK.
That is the displacement: potassium competes with calcium and magnesium for the same uptake. Come down on your PK dose rather than up on your cal-mag.

Why week 4 to 6 specifically?
Before that the plant is still stretching and the dose does not end up where you want it; after that uptake falls away and it stays behind in the medium.

1 or 1.5 ml per litre?
When in doubt, 1. The difference is a third more potassium, and that is the margin where the displacement of calcium and magnesium begins.

Do I need to adjust my base nutrient?
Measure your EC after adding. If you go over your target, pull the base nutrient back rather than the PK.

Can I give it for longer than three weeks?
Bio G Power stay with the peak weeks. Going on longer accumulates phosphate and potassium in the medium without the plant still taking it up.

Bio G Power recommend this alongside Power Top. Is that all right?
It is, but be aware that you are then supplying phosphate and potassium from two sources: this bottle gives 13% P2O5 and 14% K2O, and Power Top is declared as NPK 2-10-4. In overlapping weeks that makes the calcium and magnesium displacement above stronger. Preferably pick one, or go to the bottom of the range on both.