Smitty

Hi everyone,
I guess Id like to get compilation of everyone's information regarding managing Ph levels in hydro setups... bubblers specifically. I'd really like anyone with botanical/chemical information to share whats going on at the molecular level when various substances are used to lower Ph.
The reason Im starting this is, naturally, because of my own recent difficulties with my first grow. <Check the Nursery for a detailed description of my setup>
So here's my Ph story:
I got most of my supplies from a pet store, and the only Ph adjusting product they had was Ph Down for aquariums. It comes in a powder. The active ingredient is Sodium dihydrogen Phosphate. I figured "good enough for fish...gotta be fine for plants". I used this in the plants reservoirs all the way up until last week (day 20 of flowering). I posted in the nursery about some symptoms I was having, and was told that my plants may be experiencing sodium toxicity - which sounded completely plausible so I stopped using the stuff immediately.
I've switched to lemmon juice which needs to be added to the res daily in pretty large doses to keep the Ph optimum. The Aquarium stuff was super stable and virtually never needed adjusting.
I guess I want to know what's in the Hydoponic Ph down, and what makes it work?
And... what is happening at the molecular level when I put the Aquarium stuff in?

Thanks everybody... would be nice if we could make this so sort of comprehensive Ph Post.


Smitty

"Grow strong, and forget where you put things"

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Smitty

Takshaka

The Ph Down I'm using is 81% Phosphoric Acid. How it works I have no idea

The aquarium Ph Down you were using probably had a Ph buffer in it, as do many hydro nutrients and probably hydro Ph Down. This would explain the stability.

okitty420

This thread is of interest to me as well, since my wife and I are putting together a bubbler setup for our next grow.

We plan to use vinegar for pH down, and hydro pH up if needed. Our reasoning is as follows: Why pay $12 a quart for pH down when it is basically just an acid? (e.g. 81% phosphoric acid). Also, we've heard that most hydro nutes have some pH buffer in there. On the other hand, why screw around with grocery store alternatives that people have posted countless problems with?? We therefore decided to spend the $12 on pH up, your plants are worth it.

I slept way too much in chem. to tell you exactly how pH works, but the general idea of how to control it is simple, add an acid-solution gets more acidic; add a base-more basic. you knew that already though

peace, okitty

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Happy Gardening

nova_scotian

ph is something that has caught my interest. i plan on using a bubbler hydro-set up, and was wondering about this ph stuff. what should my ph be? ive heard 7.0, but also heard 6.2-6.3. what is the most recomended way of lowering it? where can i order this online in canada? or buy it in my small town?
can keeping a low ph be done simply by not usind hydro nutes to their full strength, and using a fresh solution as well as flushing the medium and washing the reservoir?
many aspects of ph are not clear to me, and i have read the grow guides on this matter, but they did not explain too much to me.
i am trying to get all of this information clear in my mind before i start my set up.
i will be growing 6 plants (kali mist x white widow) in rockwell cubes in gro rox, in 6 inch net pots to a 36 gallon rubbermaid container, under 250 watts of son agro HPS light. this will be a bubbler set up similiar to one that i saw in the 'my cannabis images' section. im worried that sinse i will be using a 36 gallon, the solution will be added to by gallon after gallon, where as 20 gallons or so will just be sitting there, and i heard that nute solutions after time can become acidic. how can i prevent my solution from becoming too acidic or having too high of a ph for my plants. do you use hydro nutes in your reservoir as soon as you begin? or do you wait for them to get older before you use them to not burn their roots.
Nova

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Nova Scotian

Takshaka

okitty420 - yeah , I felt exactly the same about paying a high price for Ph Down when I could use vinegar or something (which is why I didn't order it with the rest of my supplies and have had to wait for delivery delaying my growth). The way I see it though (now) is that if problems start to occur I'm not going to be wondering if it's the vinegar. Also this stuff is very strong so a litre will go a long way and last for several grows so although the initial expense seems steep you'll get your moneys worth. From what I've read hydro PH up/Down is a much more stable way of maintaining Ph levels, so in my opinion it's worth it.


nova_scotian - for hydro you want a Ph between 5.4 - 6.3 (many growers reccomend letting Ph levels drift through this range to allow optimal uptake of all nutrients), for soil growing the Ph is higher (around 6.8). The best way to adjust your Ph is by using hydroponic Ph Down and Ph Up which you buy from a hydroponics store. If you search these forums you'll find a list of suppliers, there'll be plenty of online stores in the list. As for buying locally in a small town, unless you're lucky enough to have a hydo store you're probably out of luck. Don't buy aquarium/pond Ph Down/Up, I've heard that it's no good for growing.

Before you rush out to buy Ph up or down, you've got to know what the Ph is of the water your using, if it's a high Ph buy Ph Down and vice versa. IF money's not an issue buy a good hydro Ph metre otherwise you can get a Ph test kit for aquariums.

You can't simply not use hydro nutes 'cos your plants will die - in hydro the only nutrients available to the plants are what you give it unlike soil which contains its own nutrients. Anyway, unless your lucky enough to have a water supply which is of the correct Ph the water will need adjusting anyway. Hydro nutes may change the Ph of your solution but they contain a buffer which keeps the solution at a stable Ph level making it much easier to manage and control.

When plants are young you must use a weak nutrient solution to avoid burning.

I'm not sure what you mean about the 20 gallons just sitting there - do you mean in the bubbler or do you mean you'll be storing an extra 20 gallons for topping up?

I've just started my first grow in a bubbler (first 2 sprouts appeared today ) so check out my Grow Diary.

cheers

OzGrowa

Hello folks,
Here is a few URL's that discuss PH and its role in hydroponics, some of them are hosted on commercial sites and I post them here only for informative purposes and without any endorsement of their products.

http://www.flairform.com.au/Hints%20...20Control.html
Basic review of PH and its control in Hydroponics


http://www.i5ive.com/article.cfm/4718/25808
and another on the role of PH (Nitrogen)


Enjoy folks,
OzGrowa

Drongo

Hey all,

I have been reading with interest this thread on ph.

I have never tested my ph ever. I do not get town water so all my hydro mixes are rainwater based.

My question is; Does rainwater have a known ph level? The water I receive from mother earth is very pure with very little pollution (I live in the Ranges). I would like to know if I still should test my ph?

Also, why are the ph requirements for soil and hydro different?

Drongo

Takshaka

I think you should still test your Ph. Just because you have a clean water supply doesn't mean it has the correct Ph - I am using mineral water which has a Ph of 7.8, you may well find that your water is similar. Also the Ph of the water is effected by the nutrients when you add them (as well as the soil if that's what you're using) and over time as the plants use up nutrients the Ph will drift from it's original level.

On the other hand if you've been growing successfully for some time with that water, you haven't got anything to worry about although you could probably get better results with the correct.

As to why soil and hydro have diferent Ph requirements, this is something I have pondered myself and would love to know the answer

CBD

I would recommend NOT using vinegar or lemon juice to adjust the pH of your system. Although they are both acid, they are very weak (notice there is no warning about vinegar contacting skin). This is important because these weak acids will break down quickly, causing the pH to raise suddenly, perhaps stressing your plants, or at least causing you to adjust the pH every day. If you are using bubbler system, the air being pumped into the solution will quicken the breakdown of the acid. If you have a choice, I would recommend nitric acid; because when it breaks down it should leave beneficial nitrogen. I have only used hydrochloric acid because that?s what?s around.
To lower pH, (not that I?ve ever really had to except when I added to much acid) try using baking soda, it works and is cheap.
I would like to say that I consider a pH tester basic equipment, they are cheap (under $5) and easily available and can help you keep healthy plants.

CBD

Drongo

Hey all,



Thx 4 ur replies Takshaka & CBD.



I finally got around to testing my Ph. The test results came back a solid yellow. Acid!!!I guess i nees some Ph. up I bought an el cheapo test kit (made in Aus.) from the local pet shop. I could not afford a digital ph meter so although accuracy is sacrificed I will be able to generally tell if my Ph. is Acid or Alkaline.

I noticed on one of the bottles.. Ph up I think, that it was plain old bi-barb of soda. Does anyone one know if the purity of kitchen bi-carb and aquarium 'Ph Up' differs?

I have also read that m. has very similiar cultural requirements to tomatoes. As a long time vegetable gardener I know that tomatoes like a slightly acid growing medium. Is this true of "The Divine Miss M." And................................

At what point does acidity turn to alkaline?

the drongo