Improving the setup

Hi Scott

I have bought quite a few bits and pieces from you, and was wondering if you could answer a couple of questions for me.

I have been growing for about 12 months with some success, but have been continually researching to improve yield.

I was wondering if you could run your eye over the details of my setup and see if you could suggest any improvements. I also have some questions regarding the Ph and CF levels I use.

Setup is 

Room is aprox 3.5m x 3m x 3m high


2 x 160Lt resivours with 2 x air stones each (2 x Stainless Steel 400W heaters set at 22 – 24 deg C in Winter)


4 x 32Lt containers each holding 4 x plants


Flood and Drain set up 15 mins every hour (no flood during night period)

keep an eye on the roots – not drying out, shouldn’t be too wet. Should be alright

Expanded clay in 80mm netted pots  roots hang down into tub


4 x 400W HPS Son t agro (close, but not close enough to burn)

400W only cover 1mx1m in area – do you have enough light?

750W Air Conditioner fan. I have actually set it up on an auto ramp-up, ramp down thermostat, but I found that it pumps so much air I just leave it on low  running 24/7.

ok – nice big air

3 x oscillating fans positioned around room.

ok – make sure if you were to be put into the room 24/7 with only your undies on, would you be comfortable? Or windblown, cold, stuffy, otherwise uncomfortable. Plants grow in the same climate you feel comfy in.

Ozone Generator on 24/7. It doesn’t seem to harm the plants being on constantly  I think because of the large air flow the room has

The ozone generators will increase growth through negative ion generation, as long as they don’t burn anything, I agree.

I only use 1 or 2 lights on 24/7 during grow and 4 x lights on 12/12 during flower.

May not be enough light

Nute change min 7 days, usually 14 depending on stage of growth.


Tanks / pumps / air stones cleaned with Oxyplus every nute change.


I use waterproof PH Scan1 and Saltester CF meter  calibrated every few weeks (always reads spot on).

ok – as batteries wear out, they need more often calibration or newer batteries.

I have a temp and Humidity guage that I keep an eye on. I have had problems with Powerdery Mildew in the past but hopefully the big Air Conditioner fan will solve that problem.

humidity can be a problem. Have you looked at microkill as a bio-fungicide?

Dutchfest Hydrogrow / Hydrobloom

ok good yield, flavour is debatable

PK13-14 added 3  4 weeks before harvest.

PK should be used for 1 week only.   the 6th week or 2-3 wks before harvest. No nutrients, just PK

Thats the Canna method for explosive yields.

Oxyplus added 1 to 3 times a week at 2ml / 10 Lts.


Strain is bought genetics clones.


This setup has been doing the job  but I think I could get more out of it  It doesnt produce like some photos I have seen. I think I have spent money on everything, and tried to make it right. I can leave the room for a week at a time and everything will be fine.

but consider how much certain things affect the yields.

plant type and/or strain (100%),

light levels (90%),

environment (fresh air, temperature etc) (90%)

Hydroponic System (20%)

nutrients and Additives (25%)

I am thinking that maybe I can make improvements with alterations to Nutes / Ph. I was under the belief that the optimum PH levels for hydro was 5.2  5.8 PH. Just about everywhere on the net stipulates different levels. I have been running mine at a pretty constant 5.5. I notice that on your site you recommend 6.0  6.5 with 6.3 being optimal. I also note that on the Dutchfest nutes I use it states similar range as you.

ok try 6-6.5 unless you are running rockwool, and you’ll find it much better. Major elements become less available below 6pH 

The reason why I opted for a Ph of 5.5 is because of below

graph is interesting, but I don’t totally agree with either side of it. It would depend on the ingredients used to produce the graph as well. They are specifically horticulturalist point of views, and horticulturalists generally make plant decisions that often don’t make the transition to Hydroponics.

That pH meter is amusing. But despite the drawing quality it is closer to what I feel.

plus various other threads from forums such as Ozstoners and OG.

hence the number of stories you might hear.

The idea as put to me by a chemist is to look at the elements in a nutrient solution, how much you want available, then look at pH and make the nutrients fit the availability. Hence different ideas with different brands. Some rise quickly so they recommend 5.5 so it doesn’t rise out of scale. Some I believe want you to use a lot of pH down so ask you to grow low. Some base upon soil pH. My opinion is go for the maximum of most elements solubility, which is a compromise at any stage, then use your highest quality and availability of nutrients to make the formula.

But as stated above, there are plenty of other sources that quote levels corresponding with yours.

Yes, Its disturbing that there can be different ideas. As for the idea that low pH keeps pythium at bay is intriguing. I’ll experiment with that on a system when I get a root rot next. hmm.

The next thing I am wondering about is Nute level. I was under the assumption that it is best to jam as much nutes into the plants as possible. I.e. increase CF until they start to burn, then back it off a little. In full flower I find that I can run them at around 30 + CF with no signs of burning. From memory Dutchfest recommends about 25CF.

assumption is good.

Here is the way to assess this

The higher the CF, the slower the plant uptakes nutrients. Growth is slower, woodier, shorter internodally, thicker stemmed, heavier flower or fruit, less water in produce. Too much and the nutrient uptake is too slow and the tips go brown as they can’t get the calcium up to the new growth in time.

The lower the CF, the faster the plant uptakes nutrients. Growth is faster, thinner and greener, internodal length extends, fruiting and flowering is lighter/thinner, and produce can contain a lot of water. too little, and you end up with no flowering, just lots of skinny branches producing nothing.

More light will increase transpiration which is like dropping the nutrient strength.

More airflow over the leaves will increase transpiration which is like dropping the nutrient strength.

More humidity will slow transpiration which is like increasing strength.

More temperature may (or may not if humidity is high) increase transpiration which is like dropping the nutrient strength.

More aeration makes nutrients more available which can have an indirect effect of making it seem like the nutrient strength is too high.

30CF will kill some plants, yet some will love it. It is usually strain, light levels, environmental conditions, aeration etc etc. Some will find burning at 16CF.

Observation will help you. Be very careful to have perfect looking plants, or ask “WHY NOT!” This will enhance your results.

So the right level is when you look at the plant and see what you want to see. A bushy healthy good looking flowering/fruiting plant. If its too much or too little, the look of the plant should tell you.

Even as youngsters, I find that I have to exceed just about eveyones recommended CF or the plants start to yellow off, which I have always assumed is nute deficiency  particually Nitrogen. I find that by bumping the CF up, the plants new growth greens up nicly turning a dark green colour.

In summary  ATM I have about 2 weeks to go till harvest. The PH is 5.5 and nutes are 35 CF. They look dark green and healthy with no apparent burns, but I think I should be able to get more out of them.

Do you suggest that I increase the Ph to 6.3 ?


Back the Nutes off to 25 ?

Yes and no (see above) what do they look like to you.

Change nutes brand ? Will I get any marked inprovements with a different brand ? or folair feeding ? Or Mostabud or similar ?

Yes additives might help, but its a bit late this time.

Thanks for taking the time to read this.



Hope it helps