Hi All,

I've just started my first DIY flood and drain grow and would appreciate some advice on issues with pH/EC levels and Canna Aqua A+B?

Quick explanation of setup first:

50L res feeding 3x10L buckets (clay pebbles). 1 plant per bucket. Scrog.
Feeding for 3 mins every 3 hours during lights on. Res water at 22 degrees. Room at 25 degrees. Good Ventilation.

The issue/confusion i'm having is in the setup and reading of the required pH and EC levels.

I filled the res with approx 40 litres of tap water and left to stand/heat for 24hrs. Checking the pH at this time was 7.5 approx. EC was 0.6.

I then added the nutrients (Canna state 20ml for 10L - 80ml in my case, so to err on the cautious side, i halved this amount to 40ml). So added 40ml of A and 40ml of B. pH was still 7.5.

Now i adjusted the pH by using Sodium Hydrogen Sulphate (came with our Lay-z-spa!!), and through previous trials added the correct amount to give me a pH of approx 5.5.

I then checked the EC levels and was surprised to see them sitting at 1.8!!! Checking over the last 2 days and they've crept up to 2.2!!

So i decided to do some investigating and found that when adjusting the tap water with the Sodium Hydrogen Sulphate the EC shot up from 0.6 to 1.6/1.8

If i need a feeding EC level of 1.0, should my truncheon be reading 2.6/2.8 to take into account the high EC values from my adjusted pH water, or am i doing something seriously wrong. Should i adjust the pH first, then add the nutrients (Canna says on bottle that once pH levels are set, you shouldn't have to adjust them due to the formulation of the canna product).

Plants are in and look ok, but its only day 3 so nothing really happening as yet (not died which is 1 good thing).

I've trawled through the search forums but can not find anything regarding high EC in adjusted pH water.

MrMullen and OEN: your expertise is calling, as i believe you both run the same/similiar setup

All help greatly appreciated.

Cheers

MrJRW

id start again and use some proper ph down, what is that sodium hydro,,,,,,,,, thingy bob anyway

all nutrients tell you to feed way too much

you can start at 1/4 strength and work up rather than high and suffer stress

if you find the ec is dropping then up it a couple of points when you top up

adjust your ph AFTER you've done everything else

atb

Hi storm200,

The Sodium thingymebob is a pH minus that is used for reducing the PH in swimming pools/spas. I've looked online and couldn't find anything to say it was not good to use for hydroponics.

Unless someone knows different?

Regards

MrJRW

It is also known as Sodium Bisulfate and i found this on wikipedia:

Sodium bisulfate is used primarily to lower pH. For technical grade applications it is used in metal finishing, cleaning products, and to lower the pH of water for effective chlorination, including swimming pools. Sodium bisulfate is also AAFCO approved as a general use feed additive, including companion animal food. It is used as a urine acidifier to reduce urinary stones in cats. Sodium bisulfate is considered GRAS by FDA and meets their definition of a natural product. The food grade product meets the requirements set out in the Food Chemicals Codex (FCC). It is denoted by E number E514ii in the EU. Food Grade sodium bisulfate is used in a variety of food products, including beverages, dressings, sauces, and fillings. It is also widely used in meat and poultry processing and most recently in browning prevention of fresh cut produce.

Cheers

MrJRW

still id bin it and get yourself summet suited to the job, if im understanding u correctly ure saying you ph down or sodium blar blar is throwing your ec sky high on its own??
if so that shouldn be the case and there is summet not suited in that blar blar stuff
get some ph down bud

That's correct. EC in normal tap water is 0.6-0.8, add correct amount of 'stuff' to bring pH down to 5.5-6.0 and the EC goes up to 1.6-1.8 (this is plain water, no nutes added).

I'm assuming pH down (proper) doesn't change the EC reading of the pH adjusted water?

Cheers for advice

MrJRW

hardly if any,that stuff your usin is noooo good mate

ph down only a couple of quid get some

atb storm

do you know that when you take your 1st ec reading (in your case - 0.6) you half it, so you should read it as 0.3.
its got something to do with non solvable & solvable available nutrients in fresh water,
you should have a read thru VRGs thread on nutrients & it explains it better than i can.

for a start, you don't want ANYTHING with sodium in it, it will boost ec massively, but is totally unusable by the plant. secondly, you use phosphoric acid or nitric acid for ph down, because these contain phosphorous and nitrogen respectively, which are both plant nutrients. nitric for veg, phosphoric for bloom. any type of acid added to water will make the e.c. rise dramatically, as e.c. is a measure of electrical conductivity, and acid is by definition, electrically conductive, much more so than your nutes. different acids however, will up your ec more than others, as some acids are stronger than others, so require a weaker concentration to do the job, the higher the concentration of the acid x the volume you need of it to drop the ph, the more it will boost your ec.

depending on how hard your water is, you may find to get your ph as low as you want it, you have to use a lot of acid, which will in turn make your ec go way high, so you need to compromise.

for example, i live in a very hard water area, if i add 5ml of nitric to 10l of water (and nutes at between 2.5 and 3ml/l) my final ph and ec are 6ph and 1.5 ec. if i want my ph at 5.5 however, i need to add 15ml of acid to 10 litres (ph is not a linear scale, so to drop from say 7 to 6, may only take 5ml, but from 6 to 5 will take more like 50ml!) and my ec shoots up to around 2.2........... so i keep my ph at 6

ph down will affect e.c. (and of course ph) much more than your nutes, but you must check your ec AFTER you've done everything, because your plants don't care whether the e.c. is high from ph down, or nutes, either way a high ec will burn the shit out of them. get rid of the swimming pool acid.... it's for swimming pools and get yourself some nitric and phosphoric acid, this way, when you have to start with a low ec from your nutes because acid boosts the ec so much, your acid will actually just be another type of food and not sodium which can't be used by the plants

Hi scraglor (and others),

Thanks very much for the well informed post.

Went and bought some pH down (Nitric Acid 38%) as i also live in a hard water area. Completely emptied the res, refilled with 28L of rain water and 12L of tap. Checked EC which was 0.7, pH was 7.0-7.5 (reason i put rainwater in to get the starting pH to close as 7.0 as poss!).

Added 25ml of A+B (Canna recommend 80ml for my size res - far too much me thinks), so i halved and then was cautious a bit more

Thoroughly mixed and left for a couple of hours - checked pH, still around 7.0-7.5, so i added 1ml of pH down (bottle recommended 5ml per 100L. so again i was a bit cautious - you can add but never take away ), mixed and left for an hour, rechecked and pH is approx 6.0ish with EC of 1.0

I know the EC might be a bit low (0.7 after taking into account background water EC), but the liitle girls are only 4 days in so i'm assuming a small start, increasing as the days progress?

Thanks everyone who has helped me on this, extremely grateful

Regards

MrJRW