ZTT

I am 2 weeks into flowering and the pH level of my recirculating setup is repeatedly crashing to 5.0 or below. I adjust the pH to around 5.8 with the appropriate chemicals for hydro systems. Within a couple of hours it is back down to around 5! Can I stop this....or am I running too many plants from a single reservoir? Should I get an additional reservoir and run 3 plants on each?
At the moment I have a 60L reservoir.

Im running a recirculating hydro system. 6 plants in 50L pots in 80% perlite/ 20% clay beads, under 3 x 1000W MH and 3 x 600W HPS, in a room 4.5 x 4 m, over 4200 cubic meters/hr air movement. Temp is around 27 C.

Any help would be greatly appreciated.
ZTT.

Takshaka

What nutrients are you using?

ZTT

I use "Hydro-Gro". A 3 part nutrient mix.

Part 1: Nitrogen as nitrate 6.9%, Nitrogen as Ammonia 1.7%, Phosphorous water soluable 3.8%, Potassium as Nitrate 20.3%, Magnesium 3.7%, Zinc 0.001%, Copper 0.005%, Manganese 0.1 %, Iron 0.4%, Molybdenum 0.005%, Boron 0.02%, Sulphur 4.9%.

Part 2: Nitrogen as Nitrate 14.5%, Nitrogen as Ammonia 1.0%, Magnesium 20.0%.

Part 3: Phosphorous water soluable 23.0%, Potassium as Nitrate 29.0%.

Used as follows: for every 10 litres of water add 9 grams of part 1, 6 grams of part 2 and 1.5 grams of part 3.

at a level of about 1500 ppm.

As an addative I also use "Bio-Earth Sea Acids" for chelating nutrients etc at 10ml/litre.

ZTT

Takshaka

What are you using to adjust pH?

Have you used those nutrients before without this problem? The only thing I can suggest is that you change to a different brand of nutrients, GH Flora keeps the pH very stable.

OzGrowa

The bio earth sea acids are causing the PH drop as they contain large amounts of citrates, (short acting protein donating acids).

Stop using the sea acids and the acidity should abate, a flush may be necessary. You dont need to use the chelating agent (EdTA) thats in the bio earth product.


peace,
OzGrowa